The stiffness analysis method considering uncertainty parameters of frame hydraulic press with movable eccentricity loading in the early design stage was proposed. The mathematical analytical stiffness of the upper beam with movable eccentricity loading was built. The adaptive Monte Carlo Method was used to calculate the interval of the stiffness with random parameters. The result shows that the stiffness appears higher when the eccentricity increasing. The approach has been tested by measuring the stiffness of a 10000kN frame hydraulic press and a 15000kN frame hydraulic press.