Abstract: To improve the estimation performance at low SNR, a joint blind estimator of carrier frequencies and phases for MPSK signals over single input multiple output (SIMO) channels is proposed. As the received signals in SIMO channels have the same data symbols, the proposed algorithm constructs several single tone signals by multiplying the received signals with different combinations, the carrier frequencies and phases of which are linear combination with that of the received signals. By estimation the carrier parameter of these single tone signals, overdetermined equations with the interested parameters are established. After removing the outlier data probably existed in the estimations of parameters of single tone signals, the carrier frequencies and phases estimation of MPSK over SIMO channels can be obtained by weighted least square methods. Simulations show that the proposed estimator improves the performance of carrier frequencies and phases estimation especially at low SNR levels and have a lower SNR threshold than estimators traditionally using only one receive antenna.