Embedded software design of SINS / GPS Combination Navigation System is developed, the whole design project of the software is proposed, the detailed design process of the software is given, the start-up program of the system is compiled, and the main program structure of the hold drive mode is devised in this thesis. The blended translation and edition of the assembly language and C language are adopted, which can not only optimize the run speed of the system, but also accelerate the exploration schedule of it.