Abstract: In order to study the fault distribution law of EMU pantograph in different operation stages, based on the fault data of CRH3 EMU pantograph in two different operation stages, this paper analyzed the fault distribution law with the least square estimation method. The calculation results show that the pantograph fault data of EMU obey Weibull distribution, in the early operation stage, the failure rate is high and the failure occurs frequently, and the failure rate decreases gradually in the later operation stage. By using the method of reliability data analysis, the fault distribution in different stages can provide theoretical basis for the maintenance and fault prediction of EMU running on line at different times.