Wireless sensor network has been applied in precision agriculture. This paper takes CC1000 RF as wireless transceiver, MCU MSP430F149 with high performance and Low-Power as the control center of sensor nodes, which can accurately monitor temperature, humidity and light intensity. Meanwhile, choose LM3S6918 which is a high-performance 32-bit ARM and to design sink node. Since the energy of sink node is unlimited, puts forward a new MAC protocol after experimental researches, and gives the specific methods of implementation and deployment. Experiments prove that the WSN has advantages of Lower-Power and stability. It can be competent for monitoring the general agricultural environment.