A method for updating a printer firmware is disclosed. The method achieves updating a printer firmware by use of downloading a printer firmware from the network or some media. More specifically, a Printer Job Language (PJL) Download Command of printer firmware is downloaded through an input port of the printer, such as serial port, parallel port or a network interface. The Printer Firmware Blocks of the printer firmware are then written into a nonvolatile memory of the printer, such as a Flash ROM to achieve in printer firmware updating.