1. A program management method of a flash memory, adapted to a flash memory storage device comprising a flash memory chip, wherein at least a first thread and a second thread are to be implemented within the flash memory storage device, the method comprising: defining a predetermined program unit; receiving a first write command; distributing a control right of the flash memory chip to the first thread when the first write command is determined to be executed by the first thread; and controlling the first thread to release the control right of the flash memory chip after the first thread completes a program operation of the predetermined program unit.