The board has been the focus of a federal investigation and conflict-of-interest allegations. Blagojevich spokeswoman Cheryle Jackson says the moratorium would effectively cancel the board's planned August 18 meeting.
Jackson says if the lawmakers don't pass legislation to replace the board members the governor's office plans to ask them to resign.
The board makes decisions involving multimillion-dollar hospital expansion projects that are critical in determining if the projects get financing.
Board chairman Thomas Beck didn't immediately return a call seeking comment Wednesday, and a spokeswoman said she wasn't familiar with the moratorium order.