Abstract: Compared with the traditional two-step positioning method, the Direct Position Determination (DPD) algorithm has higher positioning accuracy and stronger robustness especially in low SNR and complex environment. The addition of signal waveform information can effectively improve the positioning accuracy of DPD algorithm. However, the signal waveform in the actual passive location scenario is often difficult to be known a priori, which limits the DPD algorithm accuracy of unknown signal waveform. Aiming at this limitation, considering the digital modulation signals exist commonly in passive location system with unknown symbol information, this paper proposes a method of DPD for digital Modulation signals (MDPD) combined with waveform reconstruction. According to the digital modulation signal forming method, the ge-ometric relationship of the receive array and the radiation source, the method constructs the likelihood function of the array antenna received signal on the location parameters and the transmitted symbol, and reduces the computational complexity of high dimensional search by alternating iteration to parameter combination estimation. The simulation results verify the feasibility of MDPD algorithm with waveform reconstruction. Meanwhile, compared with two existing localization algorithms, the proposed MDPD is proved to achieve higher positioning accuracy and converge to asymptotic optimality positioning accuracy.