In order to solve the problem that the output pulse laser energy of the laser target echo simulator can not be calibrated in the field, the analog integral principle was adopted, the energy calibration device of laser target echo simulator was established through the parameter optimization design of the photoelectric detection module and the circuit structure design of the integral module, and the corresponding experiments were designed to verify the measurement ability of the calibration device. The results show that, the energy calibration device of the laser target echo simulator can accurately measure the laser energy when the pulse width is 10ns~100ns and the energy measurement range is 10fJ~1pJ. The measurement uncertainty is 13.8% when the inclusion factor k is 2. It can fully meet the requirements of the output pulse laser energy measurement and calibration of the laser target echo simulator.