Based　on　the　introduction　of　differential　oscillator　fundamental,　the　influence　of　noise　on　the　oscillator　phase　diagram　is　analyzed　emphatically,　and　the　linear　relationship　between　the　phase　diagram　size　and　signal　amplitude　is　derived　to　make　up　for　the　shortage　that　differential　oscillator　can＇t　detect　the　signal　amplitude,　the　setup　principle　of　oscillator　system　parameter　is　also　presented.　The　theoretical　analysis,　simulation　test　and　engineering　application　show　that　this　method　is　simple　and　robust,　and　has　a　good　anti-noise　property,　the　weak　fault　signals　can　be　detected　from　the　strong　background　noise,　thereby　providing　a　visual　detection　method　for　the　incipient　fault　diagnosis　of　mechanical　equipments.