Accurate　calibration　of　angle　sensor　zero-position　is　a　prerequisite　for　high　precision　control　of　permanent　magnet　synchronous　motor　(PMSM).　To　address　the　problem　that　the　existing　method　is　complicated　and　the　accuracy　is　low,　a　three-phase　PMSM　angle　sensor　zero-position　calibration　method　based　on　the　observation　of　line　back　electromotive　force(back-EMF)　is　proposed.　According　to　the　law　of　electromagnetic　induction,　the　relationship　of　the　phase　back-EMF　changing　with　the　mechanical　angle　when　external　torque　drives　the　motor　is　analyzed,　and　the　phase　relationship　between　the　line　back-EMF　and　the　phase　back-EMF　is　deduced　from　the　three-phase　motor　structure.　The　capture　of　the　line　back-EMF　waveform　is　triggered　by　signal　after　angle　sensor　crossing　zero,　and　the　zero　point　of　line　back-EMF　is　precisely　located　based　on　the　linear　interpolation　method,　and　then　the　angle　sensor　zero　position　is　obtained　by　phase　shift.　The　effect　of　angular　and　voltage　measurement　errors　on　the　accuracy　of　zero　estimation　of　angle　sensors　is　analyzed　by　perturbation　method.　The　theoretical　and　test　results　show　that　the　method　based　on　line　back-EMF　observation　can　effectively　estimate　the　angle　sensor　zero-position,　and　that　the　calibration　accuracy　of　the　method　reaches　0.018　°.　The　system　efficiency　is　significantly　improved　after　compensation.　The　method　is　convenient　and　economical,　which　is　important　to　improve　the　control　performance.　©　2023　Editorial　Department　of　Journal　of　Chinese　Inertial　Technology.　All　rights　reserved.