It’s New York City’s Grand Central of illicit sex.

A tiny Queens block has become a booming hotbed of hookers operating out of at least eight Chinese massage parlors, The Post found.

The slim strip of 40th Road in Flushing’s Chinatown, just a short walk from Citi Field, has become a 24/7 destination for sex-seeking horndogs from all over the metro area, as “masseuses” brazenly compete for johns on the narrow sidewalks.

One former NYC crimefighter said he hasn’t seen such a dense concentration of flesh factories in years.

Non-Asian men are specifically targeted by the Chinese pimps, working girls and spotters who steer customers into storefront spaces or second-floor “spas” for hour-long encounters.

It’s the same block where a prostitute committed suicide in 2017 by leaping from a building as she was about to be arrested during a NYPD sting.

Post reporters were solicited three times in the span of two hours on Friday and Saturday on the street.

In one case, the woman didn’t say a word but merely nodded in the direction of a door at 135-25 40th Road, where there is no sign in English and nothing to identify the business. A sign says “Welcome” in Mandarin.

The woman, wearing heavy dark eye make-up and red lipstick, led him up a narrow stairway to a dimly-lit pink waiting room where a gaggle of listless Asian women lounged in lingerie.

She walked the reporter into one of eight rooms, ordered him to undress, and watched while he did so — not standard practice in therapeutic massage.

The woman, who said her name was Sophia and that she came from China, offered the reporter “everything” — a known code word for intercourse in sex-trade massage parlors — for $100.

She seemed surprised when he climbed onto the table on his stomach and said his shoulders were tight.

“Oh! You want regular massage, OK!” she said. She kneaded his muscles for a few minutes, then peeled off her dress, removed her panties and pulled out a strip of condoms.

The reporter faked a back injury, put on his clothes and left.

Complaints filed with the city Buildings Department show allegations of prostitution at the address, including one in November. Inspectors tried twice in the past two months to gain access, records show, but didn’t get in.

The Post obtained shared surveillance tapes showing dozens of men entering and leaving with women, including one clad only in panties and a shirt. One tape features a man groping a young escort from behind as the two walk up the stairs together.

A business owner in the building said customers are offended by the blatant sex for sale.

“I can’t run my business because there are girls in front of the doors and they give me a hard time and my customers,” the owner told the Post through a translator.

A woman in a puffy white coat approached a second reporter outside 135-32 40th Road — the same location as the death leap in 2017 — Saturday.

“Massage?” she asked, offering a rubdown for $30.

“What else can I get?” he asked.

“What else do you want?”

“Sex,” he said.

She offered: “$80 for everything.”

“Including sex?”

“Yeah, yeah,” she said.

The reporter was targeted again minutes later at the north end of the block, near the entrance to a subway/LIRR station.

A woman in a long dark coat asked, “Massage?”

She added, “Chicky, chicky” and looked down at his groin and nodded.

The Flushing Business Improvement District says it’s identified eight brothels on that block, between Prince and Main, just around the corner from the Flushing Main Street MTA/LIRR station.

“It’s really gained a tourist image of being an illegal massage place,” said director Dian Song Yu. “That is the last thing we want to be known for.”

That many establishments would be a “large concentration,” said former Queens prosecutor Michael Musa-Obregon.

“You don’t see that,” he said. “Not for years.”

“It’s not good,” said City Councilman Peter Koo. “The least the police can do is force these girls off the street. A lady died from this and nothing has happened.”

His office said complaints made to police have been sent to the department’s vice squad, which have conducted stings and made arrests.

“These places are like whack-a-mole,” said Koo spokesman Scott Sieber. “You hit one, and they pop up in a different location under a different name. We need constant enforcement, so that the cost of doing business becomes too great for that business to sustain itself.”

NYPD Assistant Chief Patrick Conry said the department “works to end prostitution conditions which exist throughout our city, including Flushing.”

He said cops go after pimps, johns and landlords who rent out rooms to brothels — while trying to get help for victimized sex workers.

“The NYPD understands that many of the persons involved are doing so because they are being forced, coerced or otherwise made to against their will.”

Additional reporting by Kenneth Garger and Tina Moore