Workers fenced off the site at CSU on Monday ahead of an expected four-week job of knocking down existing buildings and preparing the site for the medical school.

Construction of the building is due to start in October.

The CSU-Western Sydney University Joint Program in Medicine project manager Glenn McMahon said it would take 12 months to complete.

"It is likely to be ready for occupation by November 2020, which would allow plenty of time for staff to establish themselves before [the first medical] students commence in February 2021," he said.

A learning facility will also be built at the Orange hospital precinct.

CSU Vice-Chancellor Professor Andrew Vann said it was a key milestone in the project.

"This work is a significant moment in our progression, made in partnership with Western Sydney University, towards opening the doors of the medical school," he said.

"It's also another step towards rural and regional Australians being given access to high-quality healthcare."