Abstract: A positioning algorithm of mine-used monorail crane locomotive based on strapdown inertial navigation is proposed for the problems of low positioning accuracy and high positioning cost of common positioning methods for underground monorail crane locomotives in coal mines. Nine-axis inertial measurement unit (IMU) is used to collect the acceleration data of the locomotive, and the acceleration data is pre-processed by limiting filtering and zero offset removal to calculate and output the attitude angle and acceleration values. The direction cosine matrix method is applied to filter out the gravity component contained in the acceleration data so as to eliminate the interference of this component to the data. The acceleration rate of change threshold method and zero speed correction method are used to correct the steady-state error so that the steady-state acceleration and speed are closer to the real value. The Lagrange interpolation polynomial distance measurement method is applied to measure the driving distance of the monorail crane locomotive, and the distance measurement result timing correction method is used to compensate the distance measurement error. Therefore, the positioning can be obtained according to the starting point and driving distance of the locomotive. The experimental results show that when the driving distance is 30.8 m, the ranging error is basically within 0.65 m, which can meet the requirements of high-precision and low-cost positioning.