Due to the merits of rugged structure, strong fault tolerance and high control flexibility, doubly salient electro-magnetic motor (DSEM) can compose a novel competitive aero brushless DC starter generator (SG) system. The composition and working principle of the doubly salient electro-magnetic SG system are briefly described. In response to the requirements of the special application field of aviation power supply, key technologies such as high reliability control, high efficiency and high power density control, and integrated control of the doubly salient electro-magnetic SG are summarized. The developing trends of the above key control techniques for doubly salient electro-magnetic SG are discussed.