In the process of overhead cable installation and construction, the tension monitoring of steel wire rope used for tower lifting is of great significance to construction safety. Therefore, a tension detection device based on the principle of three-point bending method is designed. The single chip microcomputer system in the device amplifies the signal obtained by the pressure sensor into the computer and converts it into electrical signal output to realize monitoring. However, there must be the interference of nonlinear factors in this method. Through experimental calibration and error compensation, the error of the device can be controlled within 2%; In practice, it is found that the measurement error caused by ambient temperature can not be ignored. Therefore, temperature compensation is carried out through temperature calibration test. The results of practical engineering data show that the measurement error can meet the engineering needs.