A weighted algorithm was put forward for SIRT algorithm of acoustic tomography.Slowness distribution regarded as the initial value was firstly obtained by BPT algorithm.The difference of slowness between each point of space and the average was seen as the weighting coefficient of the ray matrix in the SIRT algorithm.The example shows that the improved algorithm was a feasible weighting algorithm as maintaining the convergence of the SIRT algorithm,speeding up the convergence rate of SIRT algorithm,improving computational efficiency and particularly the accuracy.