With the parametric formula derivation for the elliptical-type raceway of ball-cage type constant velocity joint on the basis of the Hertz contact theory

it is found that in all of the structural parameters of the universal joint

the ball rotating diameter

the ball diameter

the groove curvature coefficient of raceway

and the contact angle has a certain influence on contact stress.Using the orthogonal testing optimum design method

and taking the size of the contact stress as the performance index

chosing the four major factors as independent variable

the ball rotating diameter

the ball diameter

the groove curvature coefficient of raceway

and the contact angle which has directly influence on the contact stress the orthogonal test is designed.By the range analysis of the result of the orthogonal test

the degree and trend which the four major factors have influence on the contact stress are got.