Abstract: In airplane alternating current electrical power system, the current harmonic on the power input side should be suppressed effectively to solve the problem of the power line conducted emission exceeding the standard in GJB151B-2013. The total harmonic current of the input can be suppressed significantly by 24-pulse rectifier technology, and some specific harmonics exceeding the standard and high frequency interferences on the input side can be filtered out by passive filter, notch filter and common mode inductors. By using these means, the requirements of the conducted emission test for the power supply can be met. Firstly, the working principle of the asymmetric 24-pulse rectifier power supply is introduced in this paper, and the current and its harmonics on the input side of the rectifier power supply are analyzed and calculated theoretically. Then, the input filter is designed in combination with the relevant limits of the conducted emission test in GJB151B-2013. Finally, a simulation model is built to verify the correctness of the theoretical analysis, and the internal parameters and structural topology of the filter are adjusted and further optimized in combination with prototype manufacturing and experiments. The whole machine test of the power supply unit verifies the feasibilities of the analysis and design in this paper.