Abstract: Auto correlation function results for a BOC signal show that it has multi-values，therefore the acquisition of a BOC signal can not simply transplant the algorithm of GPS signal. Thus，a parallel code phase search algorithm and the cross correlation characteristics of BOC signal are analyzed and the validity of parallel code phase search algorithm on BOC signal is simulated. An improved acquisition algorithm is presented and used to analyze BOC signal，addressing the insufficiencies of the parallel code phase search algorithm for the acquisition of BOC signal at low SNR(signal to noise ratio). The results show that the improved algorithm is fit for BOC(pn,n)signal where p is an integer，expanding the application area for parallel code phase search algorithms. The improved algorithm can improve SNR of acquisition 10 dB as compared to that of the parallel code phase search algorithm. The improved algorithm can enhance acquisition sensitivity of receivers，an important aid in the design of acquisition algorithms for receivers.