In view of the existing research, the method of modeling and correction using the average failure rate of distribution equipment ignores the influence of some factors, and the model research based on health index to calculate the failure rate of distribution equipment is not accurate, a method based on important parameter input and fault rate parameter correction is proposed in this paper. Firstly, the factors affecting the failure rate of distribution equipment are divided into gradual factors and sudden factors. Then, the important monitoring parameters corresponding to each fault mode are selected and the failure rate under the combined action of gradual factors is calculated by using the method based on the input of important parameters. Then, the failure rate parameter correction model is adopted to calculate the impact of major sudden factors on the failure rate one by one. Finally, the effectiveness of the proposed method is verified by an example. This method can accurately reflect the differential real-time state of different individuals of the same type of equipment by combining the real-time data of online monitoring and the influence of environment to calculate the failure rate of device.