The purpose of GAP is to ensure the safety of agro-pesticides using, but its participation rate is low. Moreover, the Agricultural Production and Marketing Groups getting GAP locate in the central, south and some sporadic areas of Taiwan. That phenomenon exposes the eating safety of people to risks. The research questions are: What is the geographic distribution of GAP? If there is any clustering phenomenon of GAP? What are the probable reasons of the spatial distribution of GAP? The outcomes are in order to make clear how to improve the participation rate of GAP and to ensure the food safety of fruits and vegetables in Taiwan. This study is based on the Agricultural Production and Marketing Groups of fruits and vegetables in Taiwan Island. By using the method of spatial analysis, this study is to verify if there is any clustering phenomenon among GAPs. For these clustering areas and the areas close to those clustering ones but rarely getting the GAPs, this study conducted the in-depth interviews with related persons for the sake of understanding if the Agricultural Production and Marketing Groups and farmers applied the GAPs and the reasons of causing these special spatial distributions. Based on the past researches, spatial analysis and the outcomes of in-depth interviews, we deduce that there should be a clustering phenomenon among the Agricultural Production and Marketing Groups getting GAP. There are five main reasons: 1. Spillover effect. If some certain farmers successfully apply the GAP, their experiences and information would be the references of other farmers in neighboring farmlands; 2. Social norms. The behaviors of farmers would be affected by the community they are belong to. For instance, membership of the same Agricultural Production and Marketing Group or friendship of the same age; 3. Externality. Since the pesticide drift would pollute neighboring farmlands, farmers who want to apply the GAP have to take the attitudes and actual farming methods of the other farmers in neighboring farmlands into considerations; 4. Crop characteristics. The natural environment of Taiwan and the market conditions would make some farming methods hard to be compatible with GAP; 5. Formal organizations. If the regional promoters of GAP, especially the farmers’ association, a vital role of promoting policies, promote the GAP policies positively or passively, the participation would be various. Last, this study would give some policy recommendations in agriculture.