CANBERRA - Western Australia has signed a bilateral agreement with China's peak economic planning body to boost trade and investment, Western Australia State Premier Colin Barnett said on Monday.

On a two-day visit to China last week, Barnett signed an unprecedented memorandum of understanding with China's peak economic planning body. It is the first time China's National Development and Reform Commission (NDRC) has signed a trade and investment co-operation accord with a state government.

"There's no doubt this is hitching our rail cart to China," Barnett told Fairfax Radio on Monday.

Barnett said China - the biggest buyer of Australia's iron ore and coal - was "certainly very unhappy" about the federal government's Minerals Resource Rent Tax targeting those two commodities.

"I think they're making a point here ... that they understand that WA does not support the mining tax and therefore are getting closer to the WA government in dealing with that and all other issues that affect their trade."

The Western Australia-China agreement covers a broad range of sectors including resources, energy, agriculture, food and infrastructure.

Barnett said the memorandum of understanding could lead to more local workers and content being used on major projects being built by Chinese proponents.

He said it would also help Chinese companies enter long-term contracts with farmers for purchases of grain and produce.