Abstract: In view of problem that positioning accuracy of positioning methods based on time ranging, namely arrival time, one-way ranging, two-way ranging and symmetrical double-sided two-way ranging (SDS-TWR) is disturbed by timing error factors such as clock asynchronization between nodes, timer frequency offset and equipment delay, an underground target positioning method based on differential error suppression optimization method was proposed. Combining with SDS-TWR positioning method, the method uses characteristics of target node as both transmitting node and receiving node to solve relationship between transmission time and length simultaneously. Irrelevant variables such as timer frequency offset and equipment delay are eliminated through matrix form and coordinates of unknown target node are only related to the measured time, so as to effectively eliminate influence of timing error on the positioning result of the target node, and achieve purpose of precise positioning. The simulation results show that compared with the one-way ranging and two-way ranging methods, the differential error suppression optimization method can effectively suppress influence of equipment delay and timer frequency offset on the positioning method based on time ranging, and can accurately locate the unknown node with high positioning accuracy, the range of ranging error is only ［-0.036 9 m, 0.037 7 m］, which is 0.012% of one-way ranging error and 0.061% of two-way ranging error.