Considering the traditional failure mode analysis problem of higher subjectivity, stronger blindness and lacking of electronic equipment historical failure data in traditional failure mode effect and critically analysis (FMECA), based on the traditional method, an improved method of failure mode analysis on the basis of based on thermal failure and sensitivity analysis was proposed. Firstly, the process of the improved method was clarified according to the existing method. Secondly, the electronic equipment temperature distribution model was established to analysis the effect of temperature on the working environment to performance degradation. Then the heated area was identified through temperature distribution,and the failure mode that caused by thermal failure was analyzed. Finally, the failure mode which has great influence on electronic equipment function was supplemented according to the results of component sensitivity. The results of application combination show that, this method combines with thermal failure analysis and functional analysis and can obtain more complete potential failure mode, while being more applicable for testability verification test.