Abstract: The evaluation of wireless communication link is crucial to the design of upper layer protocols of wireless sensor networks. Based on the statistical analysis made for a great deal of sampling values, a link evaluation model in terms of the Gaussian distribution is developed to infer the link quality or its condition between nodes from LQI (link quality indicate) values which the model is able to recognize. The model is verified and the results show that the model is extensible, i.e., it may provide the valuable reference for not only the application of wireless sensor networks, but also the simulation study on upper layer protocols.