Abstract: In order to improve the accuracy of underwater acoustic positioning,this paper proposes a real-time algorithm based on dichotomy iterative method for the sound ray correction. First, the initial grazing angle of transmission sound ray is searched out quickly by using the dichotomy iterative method, along the ray, the localization acoustic signal emitted by underwater sound source spreads. And then, the distance between underwater receiving array element and sound source can be calculated through the unique sound ray associated with this angle, this calculation process is based on Snell theorem. Finally, the positioning calculation can be completed for the underwater target by using the intersection solution of three-channel ranging values consistent with the sound ray. The testing results at the lake demonstrate that this algorithm has advantages in simple implementation and high operation speed; it is able to realize the real-time correction and improve the position accuracy of the underwater acoustic positioning system effectively under complex hydrographic conditions. This algorithm has good practicality and generality in engineering; it can also be applied to the similar underwater acoustic positioning and tracking system.