Abstract: In the course of GPS modernization, in order to avoid mutual interference between navigation signal frequency bands, the BOC modulation technology is adopted to realize rational utilization of frequency band resources. However, there are multiple side peaks in the auto-correlation function of the BOC modulated signal, which will make the acquisition ambiguous. In this paper, a new unambiguous acquisition algorithm was proposed to solve this problem. According to the characteristics of the correlation function of BOC unit, the side-peak cancellation was finally achieved by multiplying a new function after the half-chip shift and the code with polarity reversed. Simulation results show that the algorithm proposed in this paper can mitigate the interference of the side peak, reduce the main peak span to half-chip width, and acquire the same sensitivity as the ASPeCT method.However, the peak-to-average ratio is increased by about 10% and the computational complexity is reduced by 40%.