Abstract: The rice bran and wheat bran were used as the fermentation substrate to study biomass changes during the liquid fermentation process of Ganoderma lucidum JSU LIUYU18, which provided theoretical guidance for its industrial production. The uniform experiment design and SPSS regression analysis were used to construct the empirical kinetic model equations of the mycelium dry weight related to the medium composition of rice bran, wheat bran, potassium dihydrogen phosphate, magnesium sulfate heptahydrate and fermentation time. Further, the theoretical kinetic model of Ganoderma lucidum JSU LIUYU18 mycelial growth was derived by using Logistic equation as a prototype. And the difference was compared among the measured values, empirical kinetic model and theoretical kinetic model of Ganoderma lucidum JSU LIUYU18 liquid fermentation mycelial growth. The results showed no significant difference (Fcrit, P>0.05). And the two models could reflect the growth of Ganoderma lucidum JSU LIUYU18 in rice bran and wheat bran medium.