The new biological coating agent for preventing fruit rot is made of modified shellac and sucrose esters, which can maintain the quality of fruit by promoting the growth of naturally beneficial microorganisms on the fruit surface. The beneficial microbes on the surface of the fruit can inhibit rotting microorganisms through nutrient competition, while chemical preservatives kill beneficial microbes. The test results show that these two biological coating agents are superior to commercial chemical preservatives, and that fresh cane vinegar is superior to shellac.