In recent years, micro-power wireless ad-hoc network technology is a kind of bidirectional wireless communications technology for automatic and wireless control. It has features of close quarters, low power consumption, low data rate, low complexity, low cost, and of great capacity, short delay, safety and reliability of the network. The paper introduces the principles and key technologies of micro-power wireless AMR(automatic meter reading) system. A wireless AMR system based on micro-power wireless technology and RS 485 communication standard is designed, of which the corresponding software is programmed to realize the wireless transmission and automatic meter reading. The system designed has low cost, high networking speed, high reliability and good extensibility. Application shows the system designed is successful and effective.