Because of the traditional radio navigation and positioning system depends on two transmitters to precisely measure distance, Minimum Shift Keying(MSK) signal is utilized to measure distance between receiving equipment and signal transmitter. In order to minimize the impact of the signal quality and channel environment on the radio system, the spectrum of MSK signal is squared to get phase difference between two spectral lines of two frequency points. Utilizing the linear relation of phase difference and space transmission distance improves the precision of measurement. The method completes the blind estimation of propagation distance less-than code-width and does not depend on the signal synchronization. The simulation results show that, under the channel environment of more than 0 dB, the accuracy of distance estimation is less than 150 m.