Rice is one of the major food crops in China，and fertilization is an important operation links in the process of rice production, the traditional way of fertilizing rice is sprinkling the granular fertilizer on the soil surface by mechanical or manpower. This method has the problems of unreasonable fertilization, such as many operation steps, uncertain fertilization amount and uneven distribution, which directly affects the rice yield. The side deep fertilization technology for paddy field is mechanically transplanting granular fertilizer (base fertilizer and tillering fertilizer) quantitatively to the rice’s side position with a certain depth, which can reduce nitrogen fertilizer amount by 20%~30% and availably decrease pollution of freshwater resources compared with the traditional fertilization operation. It is a cultivation technique with high output, stable yield and low cost. As a core carrier for application of side depth fertilization technology, the side-depth fertilization device for paddy field has such problems as low uniform fertilization, poor stability of the device and blockage of fertilizer transmission pipelines. In view of the above problems, combined with the agronomic characteristics of side deep fertilization in the paddy field, the key components (fertilizer feeder and pneumatic conveying system) of the side-depth fertilization device for paddy field were designed and analyzed. Through kinematics and dynamics analyses, it was concluded that the bigger the rotation speed of the fertilizer wheel was, the better the uniformity of fertilizer application was. It was calculated that the theoretical limit value of the rotation speed of fertilizer wheel in the corner of the fertilizer wrap was 150r/min, and a pneumatic conveying system suitable for transporting granular fertilizer was designed. The quadratic regression orthogonal rotation combined design was used for the experiment, and the rotation speed of the fertilizer wheel, the forward speed of the device and the wind speed of the fan were taken as the influential factors. The fertilization average and coefficient of variation of fertilization uniformity were measured and analyzed for fertilization device through performance detection of JPS-12 type discharging seed test bench. Through the analysis of variance and response surface analysis by Design-Expert software, the mathematical model between influencing factors and response indexes was obtained, and the mathematical model was optimized and validated. The results showed that the coefficient of variation of fertilization uniformity was 28.25% under the condition that the rotation speed of the fertilizer wheel was 21.96r/min, the advancing speed of implement was 0.93m/s and the wind speed of fan was 22.93m/s, which could meet the minimum fertilization rate of 150kg/hm2 at the side deep fertilization of paddy field in cold region in Heilongjiang Province. The research provided a reference for the research and development of the side depth fertilization device for paddy field.