Abstract: In view of problems that underground TDOA positioning algorithm does not consider anchor position error and positioning accuracy is seriously reduced when measurement noise is large, an improved TDOA algorithm for underground positioning considering anchor position error was proposed. The anchor position error is taken as a parameter to improve TDOA positioning model, and the iterative TDOA algorithm based on convex optimization is used to solve the model. The simulation results show that the algorithm can achieve the positioning accuracy of 5 cm when position error of the anchor is 1 cm,and effectively approximate the Cramer-Rao Low Bound(CRLB) even when the measurement noise is large, which is better than the existing TSWLS algorithm and improved TSWLS algorithm.