With the wide application of multi-layer interference fit in many engineering fields, as for key component in the wind turbine generator, wind turbine’s shrink disk uses interference fit to transmit rated torque and axial force. In order to ensure the work reliability of shrink disk during the actual operation, the paper presents a more precise method on the design calculation of contact pressure on the mating surfaces with interference fit. In accordance with the order from the inside to the outside, the contact pressure of spindle-to-sleeve surface can be calculated based on the rated load required to transmit. Combining with Thick-wall Cylinder Theory and Lame Equation, taking into account the impact of fit clearance, the checking method of the bushing was used to calculate the contact pressure on mating surface of bushing-to-inner ring; and the stress analysis of the inner ring was used to calculate the contact pressure on mating surface of inner ring-to-outer ring. At the same time, the effects of frictional coefficient, fit clearance, and other design parameters on theoretical results were also analyzed. The pressure distribution of each mating surface was obtained by Abaqus software simulation, which showed that the results from improved method was closer to simulation results and had higher accuracy than traditional method by comparing the results with three different methods. Finally, the test was designed to verify whether the shrink disk could bear the load or not on the test platform of shrink disk, and the results indicated that it could meet the requirements of given loadcase.