Gear box places an important role rolling mill.Its reliability decides the machine operation.Due to the important role,if the key machine is broken because of gear box's malfunction,the whole production devices will be influeued.Therefore,it's very important to monitor the gear box online.Good monitoring system can help companies to better process fault diagnosis.The design sets up a monitoring system with Enwatch polled mode on-line acquisition module and Odyssey software.By calculating the data,the problem of the monitoring system is find,the plans to collect signal is made,the problems of monitoring gear box's multichannel vibration are solved and the malfunctions initially are estimated according to the signal,which has theoretical basis and practical meanings.