Based on the Gaussian pulse component analysis, a new deviation of laser pulse system in time-domain is defined, and its validity is further verified experimentally. The actual energy distribution of input and output optical pulses on microsecond level is gotten through high-speed photoelectric detector, and the envelops of energy distribution is fitted by Gaussian pulse components with a tolerance range of 3%. Comparing ideal values with actual values of the independent Gaussian components after getting though the system, the deviations can be calculated. According to the definition, by analyzing the changes of existed components and the causes of new components, both the physical mechanisms of optics-system interaction and the optimization of system can be studied.