Abstract: To obtain the range property of a novel combined modulation format—pseudo-random binary-phase code (PRBPC) and linear frequency modulation(LFM) combined modulation signal, the ambiguity function method is used. The ambiguity function of the combined modulation signal is calculated, the quantitative analysis formula about range resolution is obtained, and its influence factors are analyzed, whereas the simulation validation are processed. The results indicate that the key factors which influence the range resolution of combined modulation waveform are the frequency deviation and code width of pseudo-random code, the range resolution is improved along with the increase in frequency deviation and narrowing of the code width which is better than that of pseudo-random binary-phase code signal.