The invention discloses a kit and method for detecting the activity of sucrose phosphate synthase. The kit comprises an extracting solution prepared from Tris-HCl, magnesium chloride, EDTA and 2-mercaptoethanol, a reagent I prepared from Tris-HCl, magnesium chloride, 6-phosphofructose and UDPG, a reagent II prepared by dissolving saccharose in distilled water, a reagent III prepared by dissolving sodium hydroxide in distilled water, a reagent IV prepared by dissolving hydrochloric acid in distilled water and a reagent V prepared by dissolving resorcinol in ethanol and distilled water. According to the method, the influence of saccharose in a sample can be eliminated, so that the detection result is accurate, and the kit is suitable for detecting the activity of sucrose phosphate synthase in various samples. According to the kit and method, the number of reagent types can be greatly reduced, the operation can be simple and convenient, the total volume of the reaction is only 300mu L, the concentration of UDPG can be reduced on the base of not influencing the accuracy, and the reagent cost can be greatly reduced.