Abstract: The obstacles which affect the link quality of wireless sensor network can be divided into two categories by the time characteristics: one is the timeliness obstacles and the other is the permanent obstacles. The timeliness obstacles are a kind of barriers which are caused by the changes of the environment factors, and they reduce the wireless link quality. According to the properties of change in environment factors, the timeliness obstacles can be divided into periodical timeliness obstacles and sudden obstacles. Considering the periodical impact on the wireless sensor network caused by the periodic timeliness obstacles, EasiTOD(EasiNet timeliness obstacle detection) mechanism is proposed. Because the timeliness obstacles have a periodical impact on the wireless sensor network’ link, EasiTOD divides the link period into two link states: stable period and fluctuant period. Based on previous two link states, EasiTOD adopts corresponding adjustment methods of detection. Experiments show that EasiTOD mechanism can detect timeliness obstacles of wireless sensor network. With the above mechanism, EasiTOD reduces the timeliness obstacles’ interference on the communication of the wireless sensor network. EasiTOD also reduces energy consumption as much as possible on the basis of high communication reliability of network. Therefore, EasiTOD improves the overall performance of sensor networks.