Abstract: Single-epoch ambiguity resolution is always a challenging issue in the satellite navigation and positioning. With the development of BeiDou navigation and positioning system, the combination observations of three-frequency carrier phase can combine more excellent combination data, which could effectively improve the accuracy and reliability of the single-epoch ambiguity resolution. This paper adds a priori information of ionospheric delays, regards it and the location parameters and ambiguity as unknown parameters to be solved based on the traditional TCAR method and least squares collocation. Meanwhile, the ambiguity search space to be constricted by the ambiguity related method of considering ionospheric delays. The results showed that: add a prior information of ionospheric delays in unknown parameters can greatly improve the single-epoch ambiguity success rate; the ambiguity related method of considering ionospheric delays correction can reduce the ambiguity search space, and effectively improved the success rate and the reliability of single-epoch ambiguity resolution.