This　paper　proposes　an　adaptive　switching　gain　complementary　sliding　mode　control　(CSMC)　for　Permanent　magnet　synchronous　motor　(PMSM)　speed　control.　First,　the　equivalent　control　law　is　designed　for　PMSM　speed　loop　using　the　CSMC　theory.　Then,　to　avoid　the　need　of　calculating　an　upper　limit　of　the　system　uncertainties,　the　new　adaptation　law　and　hitting　control　law　are　developed.　Theoretically,　the　proposed　method　ensures　the　switching　gain　adjust　to　the　upper　bound　of　the　system　uncertainty　using　the　complementary　sliding　variable.　Compare　to　the　conventional　adaptive　approach,　the　proposed　one　can　adjust　the　switching　gain　bi-directionally　and　suppress　the　chattering　phenomenon　significantly.　At　the　same　time,　the　stability　of　the　proposed　control　scheme　is　verified　in　this　paper.　Finally,　the　effectiveness　of　the　proposed　control　approach　is　illustrated　using　some　experimental　results.