Abstract: For problem that it is difficult to online monitor multi parameters of Ingersoll Rand air compressor because the air compressor has few hard contacts, the paper proposed structure and functions of a centralized control system of mine-used air compressor based on Modbus communication mode, and focused on realization of Modbus communication method between Siemens S7-300 PLC and the air compressor. The communication method is simple in hard configuration as well as clear in programming, and can real-timely collect a lot of working parameters of the air compressor without any other sensors. The operation result showed that the system runs normally with high reliability.