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As the requirement advances for improving the working efficiency of mechanized application and the utilization rate of fertilizer, a variable-rate fertilizer spreader with centrifugal distribution cover for rice paddy surface fertilization based on the spectral sensor (Green SeekerTM) was developed to implement regional real-time variable-rate fertilization during rice growth period combining with the agronomic characteristics of rice fertilizer and near-earth spectroscopy. Spectrum detection device, decision-making and control system, variable-rate actuator and some other key techniques were designed, feedback system based on core controller STM32F103 was set up, and target application rate was responded united with expert fertilization strategy. Three-factor and three-level orthogonal performance test was carried out with setting feed gate flow rate A, disc rotational speed B and machine ground speed C as the influence factors, particle distribution coefficient of variation Cv and relative error of application rate γ as the evaluation index. By the orthogonal test, it can be known that the importance order of the factors which affected the Cv was A, B and C, and that affected the γ was B, A and C in the target spreading swath width, the comprehensive choice optimum combination of working parameters was A2B2C2, with q=300g/s, n=600r/min, v1=1.2m/s, and Cv=13.82%, and γ=9.54%, the fertilizer spreader reached the best working performance. Field tests under optimum combination showed that the average error of Cv and γ was 9.19% and 9.25%, respectively, compared with performance test. The performance of the developed variable-rate fertilizer spreader with centrifugal distribution cover was perfect and satisfied the requirement of uniformity of fertilizer and accuracy of application, which improved the performance of the centrifugal variable-rate fertilizer applicator, and it can provide certain theoretical basis for the traditional empirical fertilization.