A man has been charged after police allegedly found 150 kilograms of cheese in his car in Sydney's north-west.

Officers were patrolling in Carlingford when they stopped a black Ford Focus in Marsden Road at 3.30am on Thursday.

After talking to the 38-year-old female driver and her 31-year-old male passenger, they searched the car and allegedly found drugs.

But when they looked further they also say they found what they called "King Cheese" in the back seat and boot.

Police believe the cheese was "stolen or illegally obtained".