In order to solve the problem that power supply of the sensor in a certain type of acceleration monitor fails under the 2 kV level of EFT test, this article aims to design an optimized EFT filter based on the current typical one. In fact, the insertion loss and output voltage are both calculated by equivalent circuit. According to the comparison between the new filter and the typical one, it can be concluded that the optimized filter tends to function with better performances and efficiency, which can be confirmed by the EFT test.