Abstract: The algorithm of rapid ambiguity resolution on-the-fly for single frequency receivers is presented in this paper, Firstly, a method of QR decomposition is applied to decompose the observation matrix of satellites, so as to decrease dimensions of the matrix and to satisfy rapid ambiguity resolution by matrix transformation that can separate out the ambiguity parameter from the position parameter, the LAMBDA method is used to search the fixed ambiguity. The algorithm is applied to two different types of real data to show its effectiveness. Experimental results show that the proposed method is fast and efficient for kinematical users to make use of single frequency receivers to perform DGPS positioning. The method may be used in areas requiring accurate positioning such as navigation and geodesy.