Western Sydney residents could have access to another 600 hospital beds as NSW Labor promises to deal with a shortage if elected.

The boost will include $700 million to fund 300 beds at a new Rouse Hill Hospital in Sydney's northwest.

NSW Labor has been attacking the government over health funding as it seeks to woo voters at the state election in March.

Opposition Leader Chris Minns pointed to western Sydney's growing population and the need for suitable health services.

"It's needed infrastructure for one of the fastest growing parts, not just of the state, but the entire country," he told reporters on Sunday.

"If you don't fix Rouse Hill Hospital and build it from scratch, then you get to put too much pressure on the other hospitals in western Sydney."

The coalition government has promised to build a $300 million hospital at Rouse Hill, construction of which is due to start early this year.

But Labor's proposal expands on the plan, moving to a campus model including on-site childcare and healthcare worker accommodation.

The opposition says it will begin construction on the hospital during its first term if elected with the aim of finishing the project by 2028.

Shadow health minister Ryan Park said thousands of people were moving into northwestern Sydney.

"We are determined to make sure that the people who call this part of Sydney home, get the health care services they need and deserve," he said.

The state's health workers have held multiple strikes and actions since the start of the COVID-19 pandemic, calling for better working conditions.