In the temperature intelligent monitoring field of grain depot,it is inconvenient to transmit data by electric wire,and the wireless sensor network node has short lifetime,an ultra-low power wireless temperature monitoring system with MSP430 was designed.The entire structure and hardware module of the system based on low power were designed,which included nodes,temperature sensor module,wireless communication module,communication protocol and real-time display program.The collision problem was solved by communication protocol.The reliability of the system and the lifetime of the nodes were verified.The conclusion shows that the system has the characteristics of low power consumption,and can meet design requirement of wireless real-time monitoring system for ultra-low power consumption granary.