The low-harmonic and high-power density multi-pulse autotransformer has many advantages, such as simple structure, high reliability, high efficiency, strong overload ability, and so on. Therefore, it has a broad application prospect in aviation field. The multi-pulse rectifier power system is more and more widely used in aerospace. However, there are many practical engineering problems of the aircraft power supply characteristics that are difficult to predict. In this paper, the aircraft power supply characteristics of the rectified power system with 18-pulse autotransformer rectifier are simulated and investigated. According to the handbook MIL-HDBK-704-3, the performance of the power supply in the normal, abnormal, and fault state is verified and tested in detail. The research and discussion are carried out from six aspects: the load measurement, the steady-state limits, the voltage phase difference, the voltage transient, the frequency transient, and the power failure. The system can meet the requirements of the U.S. military standard MIL-STD-704A for the aircraft power supply characteristics. It has been applied to the radar power supply system of a large transporter, and the conformance verification test of the aircraft power supply characteristics has been completed, which provides the practical application basis for the engineering realization of the multi-pulse rectifier power supply in the radar power supply system. It also provides a reference for the development of the power supply system for other aircraft.