Abstract: To adapt the high dynamic environment, satellite navigation receivers often adopt frequency-locked loop (FLL) to assist the phase-locked loop (PLL) for carrier tracking. Based on the classic third order PLL assisted by second order FLL, the carrier phase tracking error is investigated, which is composed of dynamic stress error and thermal noise tracking error. The formulae for calculating above two errors are derived. Simulation results show that the analysis of carrier phase tracking error is correct and accurate, and it is helpful to design the carrier tracking loop feather.