Aimed at the problems that the performance is poor, the adaptability of SNR is weak, and the high computation is complex in the carrier synchronization for the CPM signal, a novel carrier synchronization algorithm based on the code assist is proposed in this paper. Firstly, a synchronization system model with CPM modulated signals is established, and in view of the above the log likelihood function of the carrier phase is deduced. Then, the parameter estimation and carrier synchronization are realized through utilizing the mean value of the posterior probability. And the estimation precision and the estimation range of phase offset are analyzed in theory. Finally, the effectiveness of the proposed algorithm is verified by the MonteCarlo simulation. The theory analysis and simulation results show that the new algorithm is good in performance in carrier synchronization of CPM signals and the adaptability of SNR, and suitable for the circumstances of large frequency offset or phase offset. Simultaneously, the algorithm is superior to the EM algorithm in the computational complexity.