Abstract: The ambiguity resolution theory of GPS L 1 phase observation using single epoch data based on DUFCOM was analyzed, the extended DUFCOM was developed. A new single epoch ambiguity fixing method was proposed for GPS L 2, L n and L w. The property of the extended method was given, f urthermore, and the efficiency of ambiguity resolution and the accuracy of positioning solution for the above four phase observations were compared in theo-ry and result.