Abstract: There is a close relationship between crop growth, development and yield formation and weather environmental conditions. In this paper, the mathematical equations describing micro-growth processes of crops (such as photosynthesis, respiration, leaf area growth, accumulation and distribution of dry matter and so on) have been established on the basis of the field experiments, laboratorial analysis and computer’s modeling tests with time interval of ten days for several years (1986—1989). It is a preliminary simplified simulation model of spring wheat growth under the optimal water and nutrient conditions. The field experiments show that simulation results of this simplified model are satisfactory.