The invention discloses a system and a method for detecting and relieving driving fatigue based on electrical acupoint stimulation. The system comprises an electroencephalogram acquisition device, an upper computer, a lower computer and an electrical stimulation instrument, an input end of the electroencephalogram acquisition device is connected to the cerebral cortex of a driver, an output end of the electroencephalogram acquisition device is connected with the upper computer which is connected with the lower computer, the lower computer is connected with an input end of the electrical stimulation instrument, and a pulse output end of the electrical stimulation instrument is connected to a meridian point, capable of reliving brain fatigue, of the driver through an electrode. The method includes: acquiring electroencephalogram signals of the driver in real time; and extracting fast-wave and low-wave frequency band signals in the electroencephalogram signals, computing a ratio of fast-wave average power spectra to low-wave average power spectra, judging the driving state of the driver according to reduction of the ratio, and controlling the electrical stimulation instrument to start and enter a corresponding working mode. Driving states of the driver are monitored in real time, and electrical stimulation is performed to the driver in good time, so that driving fatigue is relieved better, driving safety is improved, and hidden danger of traffic caused by fatigue driving is reduced.