As　a　key　indicator　for　evaluating　the　kinematic　accuracy　of　planetary　gear　train　(PGT),　lost　motion　is　affected　by　multi-source　errors　coupled　of　geometric　and　structural　errors　and　their　probability　distribution　characteristics.　A　thorough　understanding　on　the　mapping　relationship　between　multi-source　errors　and　lost　motion　is　crucial　to　the　improvement　of　kinematic　accuracy.　With　this　idea,　this　paper　establishes　a　kinematic　model　of　PGT　considering　multi-source　errors.　In　this　model,　the　structural　error　is　derived　based　on　the　time-varying　meshing　stiffness　affected　via　both　geometric　errors　and　load　distribution　on　different　power　branch.　Meanwhile,　the　uncertainty　of　geometric　errors　is　incorporated　into　the　PGT　kinematic　model　to　ensure　the　accuracy　of　the　mapping　relationship　between　errors　and　lost　motion.　Based　on　this　kinematic　model,　the　impact　of　multi-source　errors　on　lost　motion　is　revealed.　The　results　indicate　that　the　kinematic　accuracy　of　PGT　can　be　improved　through　simultaneously　optimizing　the　errors　of　sun　gear　and　any　component.　Also,　the　compound　effect　of　carrier　and　ring　gear　errors　constitutes　the　primary　cause　for　the　decrease　of　kinematic　accuracy.　©　2025　Elsevier　Ltd