[Aim] To explore the effects of different levels of aphid damage on the yield and quality of greenhouse peppers and to provide a basis for the prevention and control of vegetables, pricing according to quality, and establishment of economic thresholds for aphids.[Method] Through the investigation of aphid quantity in the field, aphid classification was carried out, and the SPAD values of pepper leaves and fruit under different aphid levels were determined. After harvesting, the number of fruits per plant was recorded and weighed, and yield indices such as fruit set rate and fruit weight per plant were calculated. Soluble proteins, soluble sugar, and vitamin C contents of pepper fruit under different aphid damage levels were also determined.[Result]Levels III and above of aphid damage caused a significant decline in yield and quality of greenhouse peppers, and the degree of decline was more significant with an increased level of aphid damage. When the aphid level reached V, the SPAD value of leaves and fruit of the pepper plant significantly decreased by 38.29% and 29.49%, respectively, the fruit setting rate by 21.28%, the fruit weight per plant by 40.09%, as well as the number of 1st and 2nd grade fruit. The amounts of soluble sugar and vitamin C in pepper decreased by 35.66% and 39.29%, respectively. The crude protein content decreased slightly, but was not significantly different between pepper and the control.[Conclusion] When aphid infestation reached more than 50 insects i.e., level III and above, yield and quality of pepper significantly decreased suggesting that this number can be considered the threshold for aphid control.