Due to the shared nature of the wireless medium,the perfbrmance of wireless sensor network is often limited by both intal interference and extal interference.The intal interference is that simultaneous traffic activity by neighboring nodes in the same network,while the extal interference is from wireless transmissions by other types of devices,such as Wi-Fi and Bluetooth nodes.In this paper,we present two channel hopping algorithms for multichannel,single-radio wireless sensor networks.The first algorithm achieves collision-free transmission environment while do not introduce extra control overhead.The second algorithm,in addition to reducing intal interference effects,reduces the extal interference effects from Wi-Fi devices.Simulation results show that both of them significantly improve performance in wireless sensor network.