The invention discloses a continuous rigid frame bridge prestress damage identification method based on deflection monitoring. The continuous rigid frame bridge prestress damage identification method comprises the following steps: I, establishing a bridge deflection monitoring system, that is, the bridge deflection monitoring system comprises n deflection monitoring devices and one data acquisition device, and the n deflection monitoring devices are respectively arranged on n deflection monitoring points; II, monitoring deflection of a bridge, namely, respectively monitoring deflection data of n deflection monitoring points on a main beam by using the bridge deflection monitoring system in real time, and synchronously transmitting the monitored deflection monitoring data to data processing equipment; III, identifying prestress damage, namely, establishing a finite element model of the bridge, processing the bridge deflection monitoring data, acquiring deflection data caused by prestress damage, establishing a damage identification rigidity matrix and identifying prestress damage. The continuous rigid frame bridge prestress damage identification method is simple in step, reasonable in design, convenient to realize, good in use effect, capable of easily and conveniently completing the prestress damage identification process of a continuous rigid frame bridge, and relatively high in identification result reliability.