Cylinder-crown integrated hydraulic press is an innovative press. The hemispherical hydraulic cylinder also functions as a main portion of crown. Compared with the conventional hydraulic press in which cylinder mounted in the crown, the thickness of hemispherical hydraulic cylinder could be much thinner and the crown section modulus could be much higher under the same application condition. As a result, the material strength capacity is better utilized. Based on sequential quadratic programming, structural optimization of hemispherical hydraulic cylinder for weight reduction has been carried out within the range of constraints including strength and stiffness conditions. Compared with the initial design, a lighter structure with weight reduction 7% and acceptable stress distribution has been obtained. Considering the advantages of cylinder-crown integrated hydraulic press, according to its optimization design, a 6300KN prototype hydraulic press has been manufactured.