To improve the disease-resistant ability and maintain good aquatic environment, experiments were carried out in 12 ponds in Beiyang Aquafarm located in Dongsheng Town of Zhongshan City by combination use of inoculating quadrivalent vaccine and beneficial microorganisms in grass carp (Ctenopharyngodon idellus) aquaculture. The results indicated that when grass carp was inoculated, antibody titer was detected 7 days later, with maximum value in 30 days, and even sustained until the experiments ended. The average survival rate of grass carp in quadrivalent vaccine immunized group was 29.7%, significantly higher than control group (P<0.01), and the relative percent survival was 90.9%. Use of beneficial microbes was useful to improve water quality, optimize the aquaculture conditions, and raise the average survival rate (7.9%, P<0.01). The average survival rate of grass carp in combination use of inoculating quadrivalent vaccine and beneficial microorganisms group was 31.7% (P<0.01) higher than control group, and the relative percent survival was 96.6%. All the average daily gain, net gain, weight gain rate and specific growth rate were increased, and the food coefficient was declined in 3 treatment groups. The profits of the 3 treatment groups were 875,1854,2 255 yuan higher than control group respectively (P<0.05). The results showed that the disease-resistant ability, the average survival rate and the growth rate of grass carp were raised, and the aquatic environment was improved by using quadrivalent vaccine and beneficial microorganisms together, showing a great synergistic effect and opening up a new way of cooperative application.