The main circuit of inverter power transform fault mode analysis in the paper, using multiple support vector machine (SVM), implements the main circuit of inverter power transform fault diagnosis. In equipment fault diagnosis, online or offline to analyze the circuit, its running state, the learning ability of neural network, the fault parameters and the relationship between the cause of the problem through neural network learning after stored in its structure and power, you can through the analysis of fault parameters, it is concluded that the cause of the problem, so as to realize the automatic diagnosis of faults. Four characteristic parameters of reflecting fault state are distilled with analysis fault types and reasons of transducer power electronic circuits. Identification of fault mode can be completed utilizing multiply support vector machine(MSVM).