Abstract: Simulation model and parameter analysis on root elongation process in wheat would provide technical basis for quantifying morphological formation and visualization of crop plant. With growing degree-day as time scale, the generation processes of primary root system, nodal root system and root branches were simulated based on the basic root unit and the synchronous relationship between root and leaf growth. The model of root developmental stage was built by calculating physiological ages of different types of root. The elongation process and total length of root were modeled with linear equations. The models were tested with independent experimental data. The comparison between simulated and measured accumulated root length and root number showed that the values of root mean square error were 370.68 cm and 1.27, and the values of relative error were 0.27 and 0.16, respectively. Sensitivity analysis indicated that the parameter variations resulted in the modest changes in simulation results, and the model performed well in predicting the dynamic changes in total root length and topological of root structure in wheat.