Forming conical parts is one of the complex and difficult fields in sheet metal forming processes. Because of low contact area of the sheet with the punch in the initial stages of forming, too much tension is applied to the sheet causing burst occurrence. Furthermore, since the major part of the sheet surface between the blank holder and punch tip is free, wrinkles appear on the wall of the drawn parts. Therefore, these parts are normally formed in industry by spinning, explosive forming or multi-stage deep drawing processes. In this paper, the effect of punch conical angle in hydroforming of conical-cylindrical parts has been studied. It is shown that by increasing the angle the thickness reduction will be reduced.