Abstract: In order to eliminate the tracking ambiguity of binary offset carrier (BOC) signal, a novel tracking loop based on subcarrier tracking was proposed. Compared with traditional tracking loop, the proposed architecture provides a subcarrier locked loop to track subcarrier. The innovative tracking loop architecture resolves the tracking ambiguity problem by tracking the subcarrier and spread spectrum code respectively. The subcarrier was synchronized with the local sinusoidal signal using phase lock loop (PLL), which exploits the periodic feature of the subcarrier of BOC signal. Figures of merit, such as code tracking error, tracking threshold and mean time to lose lock (MTLL) have been analyzed and evaluated through software simulations. Simulation results show that the novel tracking loop can improve the tracking performance of weak signal and enhance the tracking loop stability with little degradation in tracking accuracy.