This　paper　presents　an　on-line　identification　algorithm　of　stator　resistance　for　a　speed　sensorless　vector　control　system　of　general　purpose　induction　motors.　The　proposed　system　is　based　on　the　observer　theory　and　the　adaptive　control　theories.　Since　the　q-axis　estimated　rotor　flux　is　used　for　speed　estimation,　it　must　converge　to　zero　by　proportional　plus　integral　(PI)　regulator.　The　d-axis　flux　error　between　the　adjustable　model　and　the　reference　model　is　considered　to　the　caused　by　the　stator　resistance　variation　mainly.　The　relation-ship　between　this　error　and　the　stator　resistance　variation　is　analyzed　at　a　steady　state.　A　very　simple　on-line　identification　algorithm　using　the　d-axis　flux　error　for　stator　resistance　is　proposed.　The　advantages　of　the　proposed　algorithm　are　simplicity　and　solution　of　the　problems　of　system　stability　and　speed　control　accuracy　under　the　influence　of　stator　resistance　variation　when　using　only　a　voltage　model,　especially　in　low-speed　operation.　The　necessity　of　the　stator　resistance　identification　and　the　effectiveness　of　the　proposed　algorithm　have　been　verified　by　digital　simulation　and　experimentation.