One of the most important parts in the aircraft avionic system is the electrical power supply, requiring special design considerations. Thus, many international standards have been adopted to achieve the best performance and highest system reliability. In this paper, a multi-output DC/DC switching converter with new forward-flyback structure for using in the military avionic system is presented. The proposed converter can provide a main high power output and an auxiliary output for control unit. It is performed without adding extra transformer winding, or change of switching frequency and duty cycle. Moreover, demagnetizing tertiary winding will be removed. The suitable electromagnetic interference (EMI) filter, inrush current suppressor circuit, and output ripple filter are designed according to MIL-STD standards. The proposed converter has many advantages such as simplicity of design, high processing speed of control system, high power density and efficiency, low size and weight, low electromagnetic noise, and good reliability.