Abstract: In order to improve the spectral efficiency of Mary position and randompolar modified extended binary phase shift keying with continuous phase (MCPEBPSK) modulation further, both the position and polarity of phase changes are used to carry Mary information, then an Mary position and threevalued MCPEBPSK modulation is proposed. The principle of Mary position and threevalued MCPEBPSK is demonstrated, and the demodulator model based on multiclassifier as BP neural network, and support vector machine is also given. Comparisons and analysis on power spectrum, the －60 dB bandwidth, the spectral efficiency, and demodulation performance among the randompolar MCPEBPSK, the threevalued MCPEBPSK, the Mary position and randompolar MCPEBPSK, and the Mary poison and threevalued MCPEBPSK, are implemented. Simulation results show that on the premise of remaining same power spectrum structure, the new modulation method not only multiplies the bit rate and spectral efficiency, but also has better demodulation performance.