Main shaft is one of the most important mechanical components for wind turbine. Large forged parts are most being manufactured with hot open die forging. Then these components progress heat treatment process to increase mechanical properties. Heat treatment of Hollow Main Shaft is doing using forged part. One of the general defects of these parts is Quenching crack during heat treatment. In this paper, to prevent the Quenching crack, FE-Analysis is performed to determine the optimum perform design and Quenching method. This calculated results confirmed temperature, stress change and micro-structure distribution according to perform shape and cooling method during heat treatment cycle. From the results, the prototypes of Hollow Main Shaft were manufactured based on analyzed results, productivity was stable, Also To evaluate mechanical properties this part, Specimens for tensile test and impact test were taken various region of manufactured Hollow Main Shaft.