Abstract: For problems of cycle slips occurred in phase observation,the second-order difference phaseionospheric residual(STPIR)algorithm is introduced.It can remove the trend component of iono-spheric variations effectively.The algorithm is not affected by the observation interval,so it benefitscycle slip detection.At the same time,the use of MW in combination with STPIR for cycle slip detec-ting and repairing is realized.In static and dynamic data processing,experimental results show thatthe combination of MW and STPIR is accurate for cycle slips detection and repair.