According to the characteristics of fault diagnosis algorithm, the basic method of fault diagnosis algorithm based on MapReduce framework is presented. Through the analysis of fault diagnosis algorithm and MapReduce framework, the basic methods are obtained. Used traditional MapReduce framework to achieve non-iterative diagnosis algorithm. Used iteration MapReduce framework to achieve iterative diagnosis algorithm. Taking the Nearest Neighbor and Fuzzy c-Means Clustering algorithm as example, respectively. The specific implementation based on MapReduce is given. The experimental results show that the proposed method can be used in diagnostic algorithms, and provides a basis for implementing diagnosis algorithm based on MapReduce. Using MapReduce in fault diagnosis algorithm can effectively improve the efficiency of fault diagnosis.