In　this　paper,　a　convenient　type　of　movement　monitoring　system　for　knee　osteoarthritis　(KOA)　is　designed　so　that　KOA　patients　can　make　appropriate　adjustments　when　their　movements　are　not　up　to　standard.　In　the　monitoring　system,　two　MMA7361　acceleration　sensors　with　Bluetooth　module　are　worn　in　the　body　of　the　lower　limbs　to　acquire　the　triaxial　acceleration　signals,　which　will　be　sent　to　the　Android　smartphone　through　Bluetooth.　The　extended　Kalman　filter　is　used　to　filter　the　collected　acceleration　signals,　and　the　rule　induction　is　exploited　to　identify　the　standard　action.　The　statistical　recognition　percentages　for　insufficient　holding　time,　bent-leg　raise,　and　rapid　leg　movement　were　89.0%,　89.7%,　89.4%,　respectively;　with　effective　vocal　feedback.　The　results　suggested　that　the　KOA　movement　monitoring　system　based　on　Android　smartphone　was　convenient,　low　cost,　and　can　well　recognize　the　nonstandard　movement　of　patients,　which　meets　the　requirements　of　the　movement　monitoring　system.