Australia must abandon criticism of China and see the development of its largest trading partner as an opportunity if bilateral relations are to improve, Beijing's ambassador to Canberra said.

Relations between Australia and its most important trading partner have deteriorated in recent years amid accusations that China is meddling in Australia's domestic affairs. Canberra also fears China is seeking undue influence in the Pacific region.

Souring relations have strained bilateral trade, prompting some business executives to urge Australia's conservative government to prioritise economic policy above national security and human rights.

In rare public comments, Cheng Jingye, China's ambassador to Australia, described 2019 as a "mixed year" for the relationship.

"I think it is important ... to look at each other's development as an opportunity, rather than a threat," Cheng told reporters in Sydney.

Australia has for months sought to ease bilateral tensions by refraining from public criticism of China.

But in recent weeks, several senior government officials have said Canberra would not be silenced about concerns such as China's militarisation of the South China Sea, its treatment of ethnic minorities and its detention of Australian citizens.