Australia's second longest-standing prime minister thinks Donald Trump will remain president for his entire four-year term and has urged people to accept his unusual style of leadership.

Although John Howard was surprised Mr Trump won the US election in 2016, he's sure the controversial president will remain in power for his entire term.

"I think he will still be president, I really do," Mr Howard told a United States Studies Centre event in Sydney on Thursday.

Mr Trump has come under increasing scrutiny since he was elected.

John Howard has said Australians should give Donald Trump a chance. Photo: AP

But the former prime minister says Australians shouldn't be too quick to judge, insisting that while Mr Trump's style was "unusual", his actions are what matters most.

Mr Howard praised the US president's response to the war in Syria as "outstanding" in comparison to the actions of his predecessor Barack Obama.

He also complemented Australia's current prime minister for the way he has managed the relationship with Mr Trump.

"I think Malcolm Turnbull has managed him very well...I give him a 10 out of 10," Mr Howard said.

He dismissed claims the relationship between Australia and China was under strain because of Mr Trump, and disputed the idea that Australia would need to choose which country it remained allies with.

"This argument that we've got to make a choice between the US and China, if any government implemented that they would be doing immense damage to Australia's future," he said.