The invention discloses a method for simply and efficiently measuring beta-amylase activity, and belongs to field of the amylase. The method for detecting the beta-amylase activity comprises a DNS reagent color-developing method and a p-nitrophenol malt pentoside method. The DNS method is long in elapsed time, and low in sensitivity, and a beta-amylase activity value measured by the DNS method isaffected by the beta-amylase. The p-nitrophenol malt pentoside method is simple and convenient, and high in sensitivity, but only the relative enzyme activity of the beta-amylase can be expressed. So,through performing linear fitting on the DNS reagent color-developing method and the p-nitrophenol malt pentoside method, the advantages of the two methods are combined, a beta-amylase activity measuring method capable of measuring an absolute enzyme activity value of the beta-amylase is established, the method is simple in operation and high in sensitivity. The absolute enzyme activity value ofthe beta-amylase in a purified beta-amylase or an enzymic preparation mixture of the beta-amylase can be simply and rapidly measured by using the method. A result of the primary application shows thata result of the optimization method is relatively accurate, and the method can be further popularized.