The invention provides a device and method for monitoring rigidity characteristic of an elastic cushion plate under rails. The device comprises a Zigbee network transmission system and high-temperature-resistant strain gauges. The high-temperature-resistant strain gauges are melted and embedded in oblique cones of the elastic cushion plate, and deform correspondingly due to deformation of the elastic cushion plate under stress, and thus resistance variation signals are generated; the resistance variation signals are transmitted to a computer for processing through the Zigbee network transmission system, so that stress applied to the elastic cushion plate is monitored, and monitoring of the rigidity characteristic of the elastic cushion plate is realized. Through the high-temperature-resistant strain gauges in specific structures and the Zigbee network transmission system capable of realizing multipoint test, stress distribution of the elastic cushion plate in the actual use process can be monitored, and accurate monitoring of the rigidity characteristic of the elastic cushion plate is realized.