Considering the limitations that the current positioning methods havepower consumption, accuracy, etc., a NB-IoT positioning algorithm is proposed. Cloud computing is used to avoid the contradiction between the complexity of terminal equipment and power consumption; Base on the RSSI ranging model, the characteristics of wide coverage of the NB-IoT are used, and with the support of the reference terminal, the optimal strategy is used to select the relevant environmental parameters to make the ranging results more accurate. While using the least squares algorithm to obtain the target position, the constraint circle constructed by the relevant information of the reference terminal is used to determine and correct the final estimated position. Simulation and experimental results show that this method is feasible to improve the positioning accuracy; compared with general positioning algorithms based on signal strength, it has significant accuracy, and the confidence probability within 20 m error distance reaches 59.6%.