An improved pedestrian dead reckoning algorithm is proposed to solve the problem of inaccurate pedestrian location in indoor space. In the step detection stage, a three-threshold peak detection method based on motion segmentation is proposed to realize the accurate step detection of pedestrians in different motion states. Step size estimation is achieved by using an improved Weinberg model. A heading Angle correction algorithm based on the principal direction assumption is proposed to realize the pedestrian′s heading Angle correction. Finally, the information of step number, step length and course Angle is integrated to realize the dead reckoning of indoor pedestrians. Experimental results show that the improved Pedestrian Dead Reckoning algorithm has good indoor stability, and the average indoor location error <5%, which is 9.53% lower than that of traditional PDR algorithm, and improves the indoor location accuracy of pedestrians.