Abstract: APM (automatic people mover) system is widely applied in the world, having application prospect in medium and low volume rail transit both domestically and abroad. The most critical technology FAO signaling system is introduced systematically, and the technical characteristics and differences are analyzed through comparison with conventional CBTC signaling system. Taking Hong Kong airport APM with the most distinguishing features as example, from the perspective of diversified interfaces, such as fire door interface, weather station interface, and earthquake monitoring interface, the system is introduced with examples. The advanced design concept and overall technical solutions applied to Hong Kong airport line APM provides reference for the subsequent construction of APM in China.