On ball screens are the offensive skills in basketball. Due to the characters of simple and easy to execute, this skill is popular and accepted by all different levels of coaches and basketball players around the world. On ball screen can break down the man-to man defense and zone defense. International Basketball Federation (FIBA) has revised the latest basketball rules since October 1st, 2010. The major change is that the distance of the three point shot increases from 6.25 meters to 6.75 meters. This change makes defenders become more difficult to help defense. It also means more space for offensive players' penetration and passing after penetration. Because of this change, these basic basketball skills, on the ball screens, become more powerful. This article introduces the on the ball screens' definition, types, step principles and focal points by explaining the profound in simple language. We hope that this article enables basketball coaches to have a deeper ponder and the comprehension and to have an easier way on fundamental teaching.