GPS/DR integrated navigation in outdoor GPS signal better circumstances, can provide high-precision positioning and navigation, but the range of human activities is not just outside, they can also travel and stay in the various buildings. At this point, GPS signal is almost impossible to obtain, and DR will diverge due to no amendments for long time, therefore, GPS/DR system can not provide long time and high-precision navigation information indoors. For these reasons, this paper studies based on time difference of arrival (TDOA) positioning method, using ultrasonic sensors to achieve indoor TDOA positioning, and combined with the DR system to correct and improve the DR system error divergence problem, so as to enhance the navigation system positioning capacity.