The gear box is widely used in rotating machinery equipments, also it is a key component of the machinery equipment. Gear box, once it is failure, will cause serious machinery equipments failure, so the condition monitoring and fault diagnosis research of the gear box is very necessary. Its state of running and fault diagnosis can be acquired through measuring and analysis the noise of gear box. A feasible on-line LabView-based system of noise measurement on the gear box is designed by Using NI's hardware and other ordinary sound-tested equipments in teaching laboratory, as well as its applied effect is confirmed in practical test. This system realizes the signal acquisition and analysis in the online and offline conditions. It has the following functions: multiple data collection and preservation, historical data query, gearbox online monitoring and vibration quantity value alarming, etc. So, the noise detection system has very good application prospects in the actual noise detection and analysis of the gear box.