The invention provides a bridge height adjusting system. The bridge height adjusting system comprises a mechanical subsystem, an elevation monitoring subsystem and an intelligent control subsystem, wherein the mechanical subsystem is arranged between piers and a bridge body, and is used for executing the movement of height adjusting; the elevation monitoring subsystem is arranged on the bridge body, and is used for acquiring relevant information of height adjusting; the intelligent control subsystem comprises a main station control module and one or more substation control modules; the substation control modules are connected with the mechanical subsystem, and are used for controlling the height adjusting process; the main station control module is connected with the substation control modules and the elevation monitoring system, and is used for processing the relevant information of the height adjusting. According to the bridge height adjusting system disclosed by the invention, the bridge height adjusting system is arranged on the bridge, so that height adjusting of the bridge can be realized in a real-time and intelligent manner; the problems that in the prior art, the hysteresis and the uncertainty in the process of height adjusting of the bridge are solved; the efficiency of bridge height adjusting is improved; besides, continuous and real-time monitoring and adjusting of the bridge are realized; the intelligence of the height adjusting of the bridge is improved; and the safe reliability of the bridge in the process of the height adjusting is guaranteed.