The goal of modern farming system is to economize energy consumption and to reduce farming cost. Rotary tillers are the tillage tools that are used for accomplishment of both the primary and secondary tillage operations. Considering the widespread application of rotary tillers and modern tractors, optimal design of these machines is necessary. Technologies and computer capacity currently available allow us to employ design software and numerical methods to solve complicated problems in very wide disciplines of engineering. It is also important for researchers engaged in field of agriculture. In this study, for designing the matching size rotavator, a computer program was prepared in Visual Basic 6 language. Finite element analysis and Optimization of three types of rotavator blades(i.e. C type, hatchet type and L type) were carried out using Solidworks and ANSYS software.