Abstract: Aiming at the problems of laser micro energy measurement, a new method and device were advanced. This device used a set of stable power continuous wave laser, a pulse laser generator based on chopping, a special data acquisition system that included a pulse width measuring module and a pulse power measuring module, and a control software that could calculate the value of micro energy and give the correction coefficient of the calibrate energy meter by means of contrast method. The experiment results show that the laser pulse generated by this device has stable waveform, pulse power and pulse width. The pulse width measurement uncertainty is 0.08%, the laser power measurement uncertainty is 0.25%. It implements accurate replication and transfer of the laser energy of 0.1 pJ~1 mJ.