A　new　type　of　diphase　oppositing　giant　magetostrictive　self-sensing　actuator　force-feedback　water　hydraulic　servo　valve　is　introduced,　including　its　structure　and　working　principle.　The　electro-mechanical　convert　model　of　the　diphase　oppositing　magetostrictive　self-sensing　actuator　is　established,　based　on　this,　the　mathematical　model　of　the　servo　valve　is　constructed.　The　static　output　characteristics　of　the　actuator　is　simulated　in　MATLAB　and　then　analyzed,　the　result　shows　that　the　output　force　and　displacement　of　the　actuator　is　large　enough　to　be　applied　in　the　servo　valve.　The　dynamic　characteristics　of　the　servo　valve　is　also　investigated　in　MATLAB,　the　simulation　results　manifest　that　the　frequency　width　and　the　natural　frequency　are　relatively　large,　and　the　damping　ratio　is　a　little　small,　modifying　the　length　of　the　feedback　stem,　the　initial　gap　between　the　nozzle　and　baffle　or　the　values　of　other　parameters　are　effective　ways　to　improve　the　performance　of　the　servo　valve.　This　research　provides　theoretical　basis　for　the　optimal　design　of　the　diphase　oppositing　giant　magetostrictive　self-sensing　actuator　force-feedback　water　hydraulic　servo　valve　and　further　study.　©　2010　IEEE.