The invention provides a relative positioning device for satellite navigation and a carrier phase cycle-slip repairing method of the device. A satellite navigation antenna on a base station receives a navigation signal, outputs ephemerides and observed quantities of all satellites through a satellite navigation receiver and sends the ephemerides and the observed quantities to a mobile station; the mobile station receives data sent by the base station and outputs the data to a comprehensive information processing module, a satellite navigation antenna on the mobile station receives the navigation signal and outputs the ephemerides and the observed quantities of all the satellites through the satellite navigation receiver, the comprehensive information processing module performs gross error processing on data output by the base station and the mobile station, carrier phase cycle-slip detection and repairing are finished, a double-difference observation equation is established through carrier phase double-difference processing, the whole-cycle ambiguity is resolved, and relative positioning information is output. With the adoption of the device and the method, the cycle-slip can be detected and repaired in real time, outliers can be marked out in real time, meanwhile, the cycle-slip occurrence frequency can be determined, high-precision relative positioning can be realized, and the availability of a system is guaranteed.