The invention discloses a software replacing testing method applied to an airborne processor module. The method comprises the following steps that 1, functional analysis is conducted on a specific board, and a functional structure diagram of a circuit module is drawn; 2, a storage chip of circuit module software is analyzed according to the functional structure diagram in the first step, and an operation or replacement mode of the chip is researched; 3, main functions achieved by a circuit board are analyzed according to main devices on the circuit board, and design ideas and design processes for replacing the software are designed by combining the processor module; 4, program codes which enable the circuit board to achieve a self-checking function is developed according to the design processes, and software replacing is conducted; 5, checking and testing are conducted on the circuit board according to designed software functions, and original functions are restored. According to the software replacing testing method applied to the airborne processor module, function reverse operations of personnel to the circuit board are reduced, thorough testing can be conducted on the whole board, searching and locating of faults are convenient, and the software replacing testing method can be applied to rapid detection of similar boards.