Computer Aided Engineering System for crankshaft damper pulley design was developed. This system enables a designer to develop a high performance crankshaft damper pulley in a short time. This system consists of computer simulation for torsional vibration of crankshaft with a damper pulley and parametric damper pulley design program.High accuracy and easy operation are required for the simulation. New procedure of FE analysis which can accurately and easily predict stiffness of crankshaft in less than 4 hours was developed. And the database for damper rubber property which was measured under the condition of wide range enough to cover actual engine operation was created. It was shown that the calculated results agree well with the experimental results.Parametric damper pulley design program were developed. This program is composed of the design standards and stores of know-how in Toyota. Through this system designers who is not familiar with damper pulley development can design in the same ways as an expert. This system reduces design time from 5 days to 4 hours.