The purpose of this research was to analyze the three-point shot decision policy in National Basketball Association (NBA). Since the International Basketball Federation (FIBA) introduced the three-point line in 1984, three-point shot has become the crucial means to enlarge the leading range or to mend the score gap. Meanwhile, three–point shots allow players to expand the field goal range and impede the painted-area defense, making a game highly changeable and more exciting, which turn three-point shot skill a requisition to every player. Regarding that offensive and defensive records are incapable of manifesting the detail, this research took all the play-by-play game records (obtained from NBA official website) in the regular seasons of 2009-2010 as data resource and analyzed each three-point shooting moment in a 2880-second game, expecting to gain initial understanding of the three-point shot decision policy in NBA. The result showed that three-point shots are widely applied in each game. Furthermore, the three-point shot frequency in the first quarter is lower than the other three while it in the fourth quarter is significantly higher than any other. In the respect of shooting time, a climax of three-point shots appears in the last two minutes in each quarter; in the respect of score gap, the team that fell behind made more three-point shots, which is particularly significant in the fourth quarter. The conclusion is time and score gap both influence the three-point shot decision policy, which further manifests the importance of a detailed game record analysis in athletics. A play-by-play dynamic record can return the original condition of the game and facilitate detail analyses.