Abstract: Laser energy is one of the basic parameters of laser radiation and a key parameter for the evaluation of the laser source, so the calibration result of the laser energy meter has a direct relationship to the accuracy of the laser energy measurement. A factor which effect the verification result is find out through the procedure analyses of calibration of the laser energy meter. By analyses of measuring the source of uncertainty with the laser energy meter and directreading laser energy meter which were used as standard measurement devices, a mathematical model of uncertainty of measurement was built up. Two evaluation methods (Type A and Type B) of uncertainty of measurement are presented in this paper. The uncertainty of the calibration results is evaluated. The methods of calculation and expression for the uncertainty of calibration results are given.