This　work　aims　to　propose　a　trajectory　planning　technique　to　minimize　the　end-effector　synthesis　error　for　industrial　robots,　while　obtaining　a　stable　movement.　With　ER3A-C60　robot　as　a　research　subject,　the　kinematic　and　dynamic　models　are　established　by　using　screw　theory　and　Kane　equations,　and　based　on　that,　the　end-effector　synthesis　error　is　modeled　by　considering　the　effects　of　interpolation　algorithm　and　flexibilities　of　all　joints.　The　septic　polynomial　is　used　to　interpolate　the　via　points　in　each　joint　space　to　obtain　a　stable　movement.　Finally,　the　PSO　algorithm　with　suitable　parameters　is　applied　to　find　the　minimum　synthesis　error　under　kinematic　and　dynamic　constraints.　The　results　show　that　the　optimal　synthesis　error　decreases　by　88.94%　compared　with　the　initial　one,　the　angular　parameters　are　all　far　less　than　the　limitations　of　joints　and　the　optimal　movement　has　a　high　stability,　and　this　optimal　trajectory　has　better　overall　performance　than　that　based　on　the　previous　technique　(with　the　minimum　total　motion　time).　The　main　contribution　is　that　the　proposed　trajectory　planning　technique　can　significantly　improve　the　tracking　precision　of　the　end　effector　while　controlling　the　motion　time　within　a　given　span　under　the　requirements　of　continuous　path　control.