The perimeter intrusion detection system is critical to China's railway safety. An efficient intrusion detection system can effectively avoid human casualties and property damage. This article makes a comprehensive comparison of popular detection systems in recent years. It first outlines the characteristics and classification of intrusion detection systems, and then introduces the relevant literature of contact and non-contact systems according to different types, and also introduces the principles and architecture of the models they use in detail. Finally, the detection performance and suitable environment under different system models are analyzed by comparison.