Abstract: Aiming at the architecture of the lower computer of the embedded system in the field of railway signal, this paper sorted out the fault classification of the lower computer of the embedded system,gave the corresponding fault location and analysis scheme according to different kinds of faults, detailed the principle and implementation method of each fault location and analysis design, and finally put forward a comprehensive scheme of fault location and analysis for the lower computer,which was applied to the fault location of the lower machine of iBase22-TSP trackside safety platform in the field of railway signal. It improves the fault location, diagnosis and maintenance function of the lower computer of TSP platform very well.