Abstract: In order to master the principle of scraping plate fertilizer discharging in humid climate of south China, meet the agronomic requirements of rubber fertilizer application, reduce the waste of fertilizer and the pollution caused. After determining the three factors of scraper opening, scraper width and disk rotation speed, the experiment was carried out by Box Behnken central combination experiment method. The experimental results showed that the three factors had little interaction with each other, and the relationship was almost linear. The quadratic regression equation of the influence of three factors on the fertilizer discharge was obtained, and the control interval of the factors that had a great influence on the fertilizer discharge was determined, which provided a theoretical basis for the subsequent quantitative fertilizer discharge research of the scraper type fertilizer application machine.