Capacitor voltage transformer（CVT）is the most widely used electric power equipment for voltage measurement in the power grid at 110 kV and above. The performance of the equipment is directly related to the normal operation of the equipment at the secondary side. In case of short circuit in the primary side system of the CVT

the energy release process of the energy storage elements in the capacitive voltage transformer will lead to the voltage at the secondary side cannot track the voltage at the primary side well

thus resulting in transient error. The influence mechanism of transient error of the CVT is analyzed in this paper. The simulation model of the CVT is set up in accordance with the physical structure of the CVT and its equivalent circuit model. It is proposed to measure transient error by the maximum transient error and the decay time of the transient error. The influence of the main circuit parameters on the transient error of the CVT is analyzed and the variation of the transient error is analyzed based on the simulation results. Finally

the degree of influence of each circuit parameter on transient error is comprehensively compared and analyzed and the degree of influence of circuit parameters is calculated quantitatively by entropy method. The analysis results show that the degree of influence of each circuit parameter on the two characteristics of transient error is different. The simulation results have important practical value for designing CVT circuit parameters and reducing transient error.