The invention discloses an unsymmetrical pressure detector for bearing installation and an unsymmetrical pressure-preventing bearing installation method. The unsymmetrical pressure detector comprises a stationary steel bushing, a plurality of pressure sensors, a plurality of height adjustors and a data receiving terminal, wherein the stationary steel bushing coaxially hoops a detected bridge bearing, the pressure sensors are evenly arranged on the outer side of the stationary steel bushing, the arrangement heights of the pressure sensors are respectively adjusted by the height adjustors, the data receiving terminal is connected with all the pressure sensors, the bridge bearing is a round rubber bearing, and the height adjustors are evenly arranged on the outer sidewall of the stationary steel bushing along the circumferential direction. The unsymmetrical pressure-preventing bearing installation method includes the following steps: (1) surveying and setting-out; (2) installation of the bearing; (3) installation of the unsymmetrical pressure detector; (4) trial girder placement; (5) detection of the unsymmetrical pressure conditions of the bearing; (6) judgment for the adjustment of the unsymmetrical pressures of the bearing; (7) adjustment of the unsymmetrical pressures of the bearing. The invention is reasonably designed, is convenient to implement, has a good use effect, can easily and quickly detect out the unsymmetrical pressure conditions of the bearing, and can reduce or even prevent the unsymmetrical pressure phenomenon of the bearing.