Underwater Acoustic Sensor Networks (UASNs) have been widely applied in marine monitoring, military reconnaissance, hydrology surveys, etc. Their location information is an important apriori knowledge when they are carried out underwater. However, the complex underwater environments impose great challenges on location acquisition, especially for Autonomous Underwater Vehicles (AUVs), because of their mobility and finite power. In UASNs, existing location and navigation methods can offer AUVs position information, but they may either need a Doppler Velocity Log (DVL), which is inefficient due to the complex underwater environments, or they may require additional localization infrastructure to deploy underwater, which suffers from large communication latency among AUVs, and costs enormous power. In this paper, an efficient Velocity Estimation and Location Prediction method (VELP) in underwater acoustic sensor networks is proposed to avoid the above restrictions. It only utilizes collaborations based on communication among AUVs to achieve higher-precision location with lower-cost. Specifically, we apply an AUV-assisted velocity estimation algorithm with Doppler Shift estimation in physical layer of UASNs, to improve the velocity estimation accuracy instead of the DVL. Meanwhile, we build a belief propagation-neural network-based location prediction model, which decreases the communication requirements and obviates introducing modeling errors. Extensive experimental results show VELP achieves superior performance on both accuracy and efficiency, demonstrating its great advantage in offering AUVs’ location information.