The invention relates to an automatic deformation monitoring system based on laser ranging, and the system comprises a laser transmitter, a laser receiver and a data acquisition chip. The system utilizes the current mature laser ranging technology to automatically measure the structural deformation, and overcomes the shortcomings of the existing common manual reading-based level/total station measurement method, which is subjectively affected by the measurement personnel, the shortcomings of the complex construction of a connection tube measurement method and the disadvantages of low measurement accuracy of GPS measurement method and the expensive operation of the displacement test method based on image processing, and improves the effect of deformation monitoring. The system is suitable for long-term deformation monitoring of bridges, culverts, roadbeds, tunnels, slopes, building construction and the like.