The prime Minister met with Mr Chan Mo-Po, member of the executive council for Hong Kong, Joseph Yam and Chairman of the Secretaries and Futures Commission Carlson Tong on Sunday.
Mr Turnbull signalled Australia's concerns about the erosion of Hong Kong's autonomy, saying he valued an independent judiciary.
"I was talking this morning about one country two systems and the rule of law, independent judiciary strong transparent regulation here in Hong Kong," he said in an opening address.
"That is one of the key reason why Hong Kong continues to be one of the most important financial centres in the world."
Hong Kong is amid a crackdown on pro-democracy politicians and activists, which has seen some of them jailed.
The prime minister said it was important Hong Kong took action to stop Pyongyang using the Chinese territory to shift money and raise funds.
"[We need to ensure] we constantly stay ahead of the curve to ensure better service for customers, greater transparency and of course our ability to stop criminal organisations, terrorist organisations, criminal regimes like North Korea from exploiting the financial transparency and opportunities of any system anywhere in the world whether its Hong Kong, Australia or anywhere else in the world," he said.
Before the meeting, he had a discussion with Australian and Hong Kong business leaders, including from Macquarie Bank and the Li Ka Shing Foundation.
