Abstract: With the development of economy and the increase of consumer demand, the breeding from traditional farming mode gradually transition to the modern scale breeding. With the advances in breeding technology and the growing of breeding scale, investors are faced with aquaculture development opportunities. But risks are always along with opportunities. How to make the breeding enterprise risk minimum is one of the focuses of current research. At first, the article studied about the risk type and the reason of scale breeding. And then put forward the Bayesian decision model of scale cultivation, established this model and using process, made a use of Bayesian theory for the risks of scale cultivation of qualitative and quantitative analysis, and then used a case to illustrate the Bayesian decision model of the decision-making process. The results of case study showed that the Bayesian decision model was a good way to solve the problem of risk decision. The investors could make a clear judgment that whether they need to obtain complementary information. And solutions for predicting situation had made the risk calculation, which directly reflected the decision-making plan was in line with the principle of minimum risk and profit maximum. The case was a problem of scale aquaculture decision-making risk, a similar risk decision-making problem could be solved according to the decision model. Finally the article put forward policy recommendations of various risk problem to provide an effective way for the breeding of risk decision.