Magnesium has the potential of analgesia via antagonizing the N-methyl-D asparate （NMDA）receptors and inhibiting acetylcholine release from motor nerve terminal and catecholamine release from adrenal medulla and adrenergic nerve ending. Therefore magnesium sulfate may，as an adjuvant for general anesthesia and postoperative analgesia，strengthen the effects of anesthetics，analgesics and muscle relaxants，reducing the consumption of these agents.