Abstract: In inhomogeneous sound velocity field, the traditional transit time method cannot directly calculate the exact distance between the sound source and each sound receiving point, thus affecting the positioning accuracy. A high precision successive approximation sound source position method is proposed. A two-dimensional plane model is established to prove the correctness of successive approximation theory in uniform sound velocity field and fixed sound receiving formation. Then, the effectiveness of the new algorithm and the relationship between the number of iterations and the number of receiving points and the positioning accuracy are proved by simulation under arbitrary distribution of inhomogeneous sound velocity field and receiving formation. The results show that the proposed algorithm can be used to locate acoustic sources at any position in a non-uniform sound velocity field. In a horizontal region of 125 m × 125 m, the fluctuation range of sound velocity is ±5 m/s, and the positioning error can be less than 1 mm when the number of iterations is more than 26. Moreover, the positioning accuracy increases with the number of iterations and the number of receiving points.