For most high resolution DOA estimation algorithm, the number of sources should be known or estimated before. Using the acoustic vector-sensor array, the number of sources and DOA estimation algorithm is proposed in this paper, on which the blind source separation algorithm of second-rank statistic based on the particle velocity mode is extended, and the relativity difference of noise and signal between the pressure and particle velocity also be used. Through using the evaluative principle of relativity coefficient, the results of number of sources and DOA estimation is given, and algorithm is tested correctly by computer simulation finally.