３２例均属美国麻醉协会分级为１级（心功能良好），拟行择期非心脑手术的病人，随机分成三组，通过脑电功率谱观察笑气的麻醉作用，结果表明，脑电功率谱及边缘频率（ＳＥＦ）的应用可较好地评价麻醉深度，帮助了解不同麻醉药对大脑皮层的抑制特点。提示用Ｎ２Ｏ为辅助麻醉药时应适当提高吸入性麻醉药的浓度才能保证适宜的麻醉深度。 Thirty-two patients were classified as grade 1 (good cardiac function) by American Society of Anesthesiologists. The patients scheduled for elective non-cardiac surgery were randomly divided into three groups. The anesthetic effects of nitrous oxide were observed by EEG. The results showed that EEG power spectrum and The application of the edge frequency (SEF) can better evaluate the depth of anesthesia and help understand the inhibitory effects of different anesthetics on the cerebral cortex. Prompt N2O as a secondary anesthetic should be appropriate to improve the concentration of inhaled anesthetics in order to ensure the appropriate depth of anesthesia.