Abstract：GPS cycle slip is one of the important factors affecting the accuracy of monitoring results. Its multi-value and the method of judging the cycle slip of each frequency are particularly important. In this paper, for the detection of dual-frequency cycle slip, we use ΔΦ=ΔN1－(λ2/λ1)ΔN2 as the master equation and propose a method to detect the cycle slip using the Grubbs criterion, restricting the ΔN1、ΔN2 search range of dual-frequency cycle slip to calculate the integer solution satisfying the master equation. Through the verification of GPS data with a sampling rate of 1 s, 5 s and 15 s, the method in this paper not only solves the problem of multiple values, but also accurately detects the cycle slip at all frequencies with a success rate of 100%.
