The enhanced functions and complex structure of agricultural machinery lead to serious consequences of failure. During reliability analysis of products, many evaluation elements are involved and failure information and evaluation indexes are fuzzy, so it is difficult to give credible and accurate analysis results. In view of these problems, the fuzzy comprehensive evaluation was introduced into the traditional method of failure mode effect and criticality analysis (FMECA), and the new FMECA analysis method based on fuzzy comprehensive evaluation was formed. Factors set, evaluation set, judgement matrix for fuzzy factors and weights set were established to quantify the qualitative evaluation index. Taking the vertical corn threshing test bed as a case, analysis table for failure modes and effects analysis (FMEA) was established and criticalities of failure modes in the table were evaluated. According to the criticality, failure modes were ranked and emphases of reliability improvement were found. The analysis procedure and method were verified. The result showed that the method had obvious accuracy and comparability, which provided scientific and accurate decision basis for the structural optimization and formulation of maintenance program of agricultural machinery.