The purpose of this study is to examine tracks and rotations of basketball balls between basketball players with and without shooting aid at free-throw. Method: This study recruited 3 male basketball players with different position (small forward, power forward, center) and they performed 20-times free-throw with shooting aid or without shooting aid separately. We filmed the actions of free-throw from lateral and back as well as used computer to operate image processing to analyze ball's track and rotation. Conclusion: when players wore shooting aid, the trajectory of the ball was obviously higher than players who did not wear. The variance of ball's rotation from former also decreased efficiently. We inferred that the shooting aid can assist the subjects to improve the stability of free-throw significantly. The future study and application were discussed in the article.