In this paper, sensors, which are directly installed on the surface of the mill, are used to collect mill's signals by wireless. The frame of the system is introduced and the hardware and software is designed in details in this paper. With the transmission mode of I2S and MCU of AT89S2051, the transform from analog signals to digital signals , data's transmission by wireless is achieved by this system. On this basis, the program designed is not only good at collect mill's signals, but also restraining the interference, analyzing spectrum. So the program can effectively achieve the mill state detection.