The invention discloses a method for improving the fruit set percentage of Japanese pepper, which grafts a plurality of androphore on a female plant of the Japanese pepper, and a setting ratio of the androphore to the female plant are 8-10:1. In the method, a certain amount of androphore are grafted on the female plant of the Japanese pepper to form monoecism so as to shorten the distance of male flowers and female flowers, improve the activating probability of bee and other pollination insects on the male flowers and the female flowers; and meanwhile, the probability of transferring pollen on the female flowers through anemophily is improved, so that the fruit set percentage can be greatly improved.