Abstract: The effect of nitrogen on the fruit growth and development of sweet pepper( Capsicum frutescens var. grossum )were studied by soluble culture. The results showed that it was difficult to set the first fruit of sweet pepper under the condition of nitrogen excessive. Therefore, fruit harvest delayed over 7 days at least and it could loss the chance of come into the market. The comprehensive effect of nitrogen on market fruit yield and characters indicated: The highest market fruit yield was obtained under moderate nitrogen level (middle N), because of the highest percent of fruit harvested on every fruit set positions of branch. However, the lower and excessive nitrogen nutrition decreased the fruit yield of sweet pepper. It was found that the behavior of setting fruits of sweet pepper was depended on its botany characteristics. The promote or delay of nitrogen on the fruit development might have more effect on fruit setting amounts on some degree. The model of yield or amount of fruit setting could be described as Y = 2(n- 1) under moderate nitrogen nutrition when the sweet pepper was trained with two main branch and one main stem on a single plant. Compared with the theoretical yield and practical yield of sweet pepper obtained in the experiment, it was found that there was the consistent in fact, and forward the application foreground of the model was discussed.