Abstract: SNR is a crucial parameter of the detector. In this paper, it was mainly concentrated on the analysis on the relationship between the integration time and the SNR of the domestic 640512 MWIR cooled detector. Based on the theory of the fact that the integration time is corresponding to the signal and the noise, a lot of work was done which focused on these two aspects in the separate way when the detector was working under the normal condition. A large number of experimental data was analyzed which demonstrated the increasing relationship between the detectors output signal and the noise signal while the integration time was changed. The experimental and the theoretical analyzed results both concluded the impact of the integration time to the SNR. Finally, the most optimal integration time was submitted.