The invention discloses a device for detecting bearing mounting eccentric compression and an eccentric-compression-preventing bearing mounting method. The device comprises a fixed steel lantern ring,a plurality of pressure sensors, a plurality of height adjusting devices and a data receiving terminal and is characterized in that the fixed steel lantern ring coaxially sleeves a to-be-detected bridge bearing, the pressure sensors are arranged on the outer side of the fixed steel lantern ring, each height adjusting device is used for adjusting the arranging height of the corresponding pressure sensor, the data receiving terminal is connected with the pressure sensors, the bridge bearing is a circular rubber bearing, and the height adjusting devices are evenly arranged on the outer lateral wall of the fixed steel lantern ring along a peripheral direction. The eccentric-compression-preventing bearing mounting method includes the steps of firstly, surveying and setting out; secondly, mounting the bearings; thirdly, mounting the device for detecting the bearing mounting eccentric compression; fourthly, laying down a girder; fifthly, detecting the eccentric compression conditions of the bearings; sixthly, judging whether bearing eccentric compression regulation is needed or not; seventhly, regulating bearing eccentric compression. The device is reasonable in design, convenient to implement, good in use effect, capable of simply and fast detecting the eccentric compression conditions of the bridge bearings and capable of reducing even avoiding the bearing eccentric compression.