Complex microbial preparations are a class of effective biological control agents that play an important role in agriculture and aquaculture. In this study, the Penaeus penicillatus was used as the test object. Four microbial preparation treatments were arranged (Group 1~4) with the microbial agents accounted for 0.0%, 1.0%, 1.5%and 2.0%of feed quality, respectively. Group 1 was set to be the control without any microbial preparations insertion. The whole experiment lasted 33 days. To investigate the effect of microbial agents on the growth of prawn, several data had been measured, such as the growth performance of prawn, the properties of the bottom mud and water quality. The results showed that there were no significant differences in the body weight of the four groups before experiment (P>0.050). After the experiment, the body weight of each experimental group was higher than that of the control group (P＜0.050). Above all, the body weight of group 4 was(0.60±0.03)g, indicating that the use of complex microbial preparations promoted the growth of prawn. Meanwhile, there were also significant differences in the number of Vibrios in water between different times of the experiment (P=0.000). The number of Vibrios in the control group displayed an upward trend. On the 30th day, the number of Vibrios in the control group without microbial agents was the highest, indicating that microbial agents could control the growth of harmful bacteria in aquaculture water environment. The DO value in the water was significantly different in different culture time (F=191.959, P=0.000). The content of NH4-N、NO2-N and NO3-N was similar to the above. The F value was 250.633,659.806 and 1 937.649, respectively, whereas P value was 0.000. After the 10th day of culture, the DO content in the experimental group was higher than that in the control group, whereas the NH4-N, NO2-N and NO3-N value in the experimental group were lower than that in the control group. In summary, the compound microbial bacteria agent can obviously promote the growth of prawn and purify the breeding environment to a certain extent.