The mismatch between synchronizing pulse period and scanning speed in linear array detection will decrease the total level of optical transfer function of aerial camera． It can provide effective judging criterion by analyzing the relationship between the deviation and system modulation transfer function． Taking a certain aerial camera as an example, the principle of linear array TDI detection imaging is introduced, and a calculation method from deviation of scanning speed to system moving optical transfer function is given． Further more, it is given that the effect of scanning speed deviation on the system MTF． Experiment results show that the error between system’s moving MTF by statistical method and the measurement is less than 5%, and it can be used in judging the effect the deviation of scanning speed on the moving MTF．