Abstract: In order to speed up drying speed of forage in the field，a steel roller forage modulator was designed.Solidworks was used to model it，force analysis and parameter setting of steel roller were carried out，and simulation module was used to simulate steel roller，optimized design was carried out.Result showed that when modulated steel roller was made of 45 quality carbon structural steel and spoke thickness was 8mm，it would be subjected to less stress and strain，and safety factor was higher.Results of field experiments showed that flattening rate was up to 94% when a pair of steel rollers were meshed with each other，which met requirements of modulator on performance index of forage harvest and improved design efficiency and accuracy.