Abstract: An algorithm suitable for carrier phase and frequency offset estimation in software radio is proposed. Firstly the carrier phase with frequency offset is obtained with a parallel method. Then the phase trajectory is estimated based on MMSE criterion, and the frequency offset and initial phase can be achieved. The algorithm suits for linear and nonlinear modulation, which is simple and can be realized all-digitally. The simulation for QPSK shows that the algorithm can estimate the carrier phase and frequency offset accurately and reduce the system BER effectively.