Abstract: 【Objective】Protein content of grain is an important quality index of rice product. Analyzing the dynamic rule of nitrogen assimilation and translocation in rice plant and relationship, this study will development a simulation model on formation of grain protein based on the development process to predict rice grain protein content and yield under different ecological environmental conditions.【Method】On the basis of the field experiments with different cultivars and nitrogen levels, using physiological development time (PDT) as general time scale of development progress, the fundamental dynamic relationships between plant nitrogen accumulation and translocation and environmental and genetic factors were quantified and a simplified and explanatory simulation model was established to predict the processes of nitrogen uptake and partitioning in plant and protein formation in grain of rice by integrating with a rice growth model (RiceGrow).【Result】The model was validated using the data sets of different years, eco-sites, varieties, N fertilization and irrigation conditions with the RMSE 0.22%-0.26%. The results indicate that the model is accurate and applicable for predicting grain protein content and grain protein yield of rice under various environments.【Conclusion】Using PDT as general time scale of development progress, this study developed the simulation model on rice grain protein formation based on nitrogen assimilation and translocation, which might predict rice grain protein content and yield under different ecological environment conditions, and expanded and perfected the exist rice growth models on quality prediction.

Key words: Rice, Nitrogen accumulation, Nitrogen translocation, Grain protein, Simulation model