1. A program management method of a flash memory, adapted to a flash memory storage device comprising a flash memory controller and 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 by the flash memory controller; receiving a first write command by the flash memory controller, wherein the first write command is corresponding to a first program data, wherein a quantity of the first program data is bigger than a quantity of the predetermined program unit, wherein the predetermined program unit includes at least one physical page; 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 by the flash memory controller; controlling, by the flash memory controller, the first thread to release the control right of the flash memory chip each time in response to a completion of programming data into the predetermined program unit by the first thread; determining, by the flash memory controller, whether the second thread requests the control right of the flash memory chip in response to the releasing of the control right of the flash memory by the first thread; and distributing the control right of the flash memory chip to the first thread if the second thread does not request the control right of the flash memory chip by the flash memory controller.