Abstract: With the increasing complexity of modern electromagnetic environment, navigation receiver is at higher risk of various interference. Narrowband interference and pulse interference are common means of suppressing interference on satellite navigation signals. Different interference signals have different time-frequency domain characteristics, and their influence on satellite navigation signals is also very different, which is mainly reflected in the carrier-to-noise ratio and bit error rate. In view of the lack of research on pulse interference performance in China, a formula of anti-interference quality factor suitable for pulse interference is proposed by comparing narrowband interference performance evaluation method. This paper deduces the method of calculating the equivalent carrier-to-noise ratio in time domain under pulse interference, and verifies the result through simulation. The result shows that the calculation error of equivalent carrier-to-noise ratio under pulse interference with different duty ratio is less than 0.5 dB, and the result is quite accurate.