In the field of Beidou navigation and positioning, in order to obtain accurate carrier phase observation data, the cycle slip phenomenon in carrier phase observation must be effectively detected and repaired. This paper first constructs single-difference and double-difference detection quantities, then using wavelet transform to three-scale decomposition of single-difference and doubledifference detection sequences,and extracting high-frequency coefficients and low-frequency coefficients at the same time. Obvious cycle slips can be observed from singular values of high-frequency coefficients. Then, the singular values of high frequency coefficients are replaced by Lagrange linear interpolation, and the high frequency coefficients and the low frequency coefficients are reconstructed. Finally, the reconstructed signal is subtracted from the original signal to obtain the cycle slip difference value, which is used to repair the cycle slip layer by layer. In the experiment, 200 cycle-free epochs were selected, and different cycle slips were added at 100 epochs. Simulation results show that the method can effectively detect and repair cycle slips of more than 0. 5 weeks.