Abstract: Stable, real-time and accurate link quality estimation in wireless sensor network is critical for guarantee the upper layer protocol performance, load balancing and power control. This study proposes a link quality evaluation model which describes the relationship among PRR (Packet Received Rate), transmission distance and transmission power. Based on real platform, a large number of experiments are done. After analyzing the collected data, a new link evaluation model based on three-dimensional space is established. Experiment results indicate that the model only need to know the transmission distance and transmission power, then the PRR can be obtained conveniently. It decreases energy consumption compared with sending probe packets to count PRR.