Abstract: Based on our researches on High Gradient Magnetic Seperation (HGMS) and machine wear particle characteristics when wear takes place in machanical systems, the idea of applying HGMS to machine's Wear Monitoring and Fault Diagnosis (WMFD) is put forword. Then it describes a newly developed instrument——Wear Particle Monitor (WPM) as an example of HGMS's application in the field of WMFD.