The invention discloses an efficient slow-release urea. The efficient slow-release urea is prepared by coating urea by utilizing a coating slow-release solution and drying and solidifying the coated urea, wherein the coating slow-release solution consists of the following components in percentage by mass: 1 to 5 percent of gamma-polyglutamic acid, 1 to 5 percent of nitration inhibitor, 0.5 to 5 percent of adhesive, 0.05 to 2 percent of surfactant and the balance of water; and the pH of the efficient slow-release urea is 5.5 to 6.5. The invention also discloses the preparation method of the efficient slow-release urea. The gamma-polyglutamic acid in the efficient slow-release urea has the effects of coating and chelating the urea and the nitration inhibitor, so that separation of the nitration inhibitor and a nitrogen fertilizer is reduced, leaching and runoff losses of nitrate nitrogen are reduced, one-time fertilization can be realized, top dressing is not required, the utilization rate of the fertilizer can be improved by over 15 percent, and the yield of the crops is increased by 10 to 30 percent.