Abstract: In designing farmvehicles the most important problem is how to obtain the most efficient and stable braking property. According to the mechanical analysis of farmvehicles driving, the limited equation of the brakeforce distribution ratio strength was given. The influence of parameter selection of main elements of the braking system on the braking property was also discussed. An optimized design method to get better braking property was prodded under various braking strength. By this method, a simulate calculation and experiment were made in a range of adhesive efficiency of common roads. Under this optimized design method, the strength of calculation was movably cut down and a primary preview could be obtained.