This　paper　aims　at　the　head　mounted　display　(HMD)　equipment　based　on　smart　phones,　puts　forward　ainteractive　mode　in　order　to　improve　the　immersion　of　virtual　reality　(VR)　games　and　applications.　Its　core　is　a　real-time　humanmotion　analysis　algorithmbased　ontri-axial　acceleration　(TA)　sensor.　This　algorithm　uses　smart　phone　built-in　sensor　to　obtain　the　real-time　TA　signal　produced　by　human　movement,　after　the　processing　and　classification　to　the　signal　through　the　threshold　value　method　to　classify　motion　state　of　user,　such　as:　stand,　walk,　run　and　jump.　Then　the　results　directly　reflected　in　the　virtual　scene,　make　user　do　the　same　behavior　in　VR　games　and　applications.　The　experimental　results　show　that　the　algorithm　can　quickly　and　accurately　determine　some　motions,　ensures　that　the　user　can　get　higherimmersion　in　VR　experiences.