The specialization of agriculture is an important aspect in the change of agricultural management.This paper expounds the main mode and decision mechanism of farmer’s participation in the horizontal division of labor and specialization and builds the index of farmers planting division of labor and specialization.Based on the questionnaire of Guangdong province,this paper measures,analyzes and compares the influencing factors of farmer’s planting horizontal specialization.The result shows that the specialization degree of grain is greatly influenced by land scale,higher degree specialization shall be matched with larger scale,that is,larger planting areas and comparably smaller land fields.Specialization degree of vegetables is slightly influenced by land scale,while weakness of agricultural labors is not influenced by it.Fruits and flowers are largely affected by land scale,market,labor weakness,capital investment,transportation in villages.Therefore,this paper puts forward some relevant suggestions.