The purpose of this study was to identify individual joint angles and relation of joints participated in flat serve of tennis. The 3-d angle was calculated by vector projected with least squares solution with three-dimensional cinematography. The motion planes in the shoulder joint were classified in the flexion/extension, abduction/adduction, horizontal abduction/adduction, and medial/lateral rotation. The Flexion and internal rotation of the shoulder joint were distinguished from the other angles. Specially the internal rotation almost exactly maximized increasing angular motion at impact and made clear in patterns of the angle. An angular motion of trunk was not significant in respect to starting serve motion in linked segment system. But Knee joints was likely presented much important to contribution to powerful angular motion of the upper extremities by means of maximizing extensive angular velocity before their explosive angular motion. The both side of knees were simultaneous in the flexion and the extension before impact. The instant of racket`s rotating to a vertical axis in the inertial axis made much change of angular motion among joints. In comparison with impact time(90.94%±1.82), the knee joint extended first of all(72.30%±3.97), the shoulder joint flexed, the trunk internally rotated, then the elbow extension and finally the shoulder internally rotated orderly(90.20%±1.16).