Abstract: Environmental Kuznets Curve (EKC) hypothesis is a presumption that environmental degradation follows an inverted U-shaped trajectory in relation to economic growth. The thorny question of whether economic growth has a cure of environmental degradation has sparked large-scale empirical studies in the last decade, whose conclusions has been mixed at present. In this paper, the EKC model was used to verify whether relationship between agricultural non-point source pollution and economic development in Taiwan Region has an inverted U-shaped curve. Input density of chemical pesticide, input density of nitrogen and phosphorus fertilizers, chemical oxygen demand (COD) output of livestock and poultry’s manure and urine were selected as indicators of agricultural non-point source pollution (the dependent variables). Then per-capita real GDP was used as the indicator of economic growth (the independent variable). The results showed that the relationship between input density of chemical pesticides and per-capita real GDP was not fitted the typical EKC characteristics and also without any turning point. The relationship between COD output of livestock and poultry’s manure and urine and per-capita real GDP was typically fitted an inverted U-shaped curve with a turning point falling in the mid-1990s. The relationship between input density of nitrogen fertilizer and per-capita real GDP had typical EKC characteristics with the turning point falling in early 1990s, while the relationship between input density of phosphorus fertilizer and per-capita real GDP had typical EKC characteristics with the turning falling in early 1980s. The results suggested that with the development of economy, pollution due to breeding of livestock and poultry and chemical fertilizers application initially increased and then dropped. Economic development had a positive effect on pollution due to breeding of livestock and poultry and chemical fertilizers application, but now, the pollution had been under control. While the consumption of chemical pesticides in Taiwan Region had always been very high, economic development had no significant effect on input density of chemical pesticides. According to Maslow’s hierarchy of needs, people’s requirement for environmental protection had been becoming stronger with economic development. During the 1980s to 1990s, breeding quantity of livestock in Taiwan Region was limited. However, the breeding mode and treatment of livestock and poultry manure and urine had improved considerably over time. Thus COD output of livestock and poultry’s manure and urine had dropped. Meanwhile, soil pollution by chemical fertilizers had long been known and therefore mostly replaced by organic manure and green manure without a significant effect on crop yield. This had steadily reduced the input density of chemical fertilizers in Taiwan Region. As the climate and geography of Taiwan favor biological diversification, there is always severe pest and disease damage in the region. Although pollution from chemical pesticides is well known, the consumption of chemical pesticides in Taiwan Region has still not changed. Thus high efficiency and low residue is the main direction of study on the use of chemical and biological pesticides.