Abstract: In order to obtain the optimal extraction process of GABA from Ganoderma lucidum mycelia, the two-stage cultivated Ganoderma lucidum mycelia were taken as the research object, and the GABA from Ganoderma lucidum mycelia was extracted through the water extraction method. The optimal process conditions were determined by using the single factor and orthogonal experiments. The results showed that the most important factor affecting the extraction of GABA from Ganoderma lucidum mycelia by water extraction was the extraction time, followed by the ultrasonic power, the ratio of material to liquid and the extraction temperature. The optimum extraction process was obtained by orthogonal test: the extraction time of 80 min, the ultrasonic power of 300 W, the extraction temperature of 80℃, the ratio of material to liquid of 1∶30. Under these conditions, the content of GABA reached 1.700 mg·g^-1.