Abstract: To solve problems of complex wiring, unstable data transmission and difficult maintenance of existing hydraulic support monitoring system in coal mine underground, a pressure monitoring system of hydraulic support based on Ad-Hoc networks was designed. The system can solve complex wiring problem via bluetooth technology to form a wireless Ad-Hoc networks, and adopts bluetooth wireless communication and Ethernet to transmit hydraulic support pressure data with fast transmission rate and stable performance. Staff can real-timely analyze hydraulic support pressure value by use of PC software.