兒童肥胖及其相關議題已是全球的流行病並逐漸受到政府與人們重視。本研究主要目的是探討學齡期兒童運動參與特性與對身體質量指數。研究對象以97年度上學期就讀於台北市立六所國民小學5、6年級的學童為主要研究對象。抽樣期間為97年10月。在問卷發放的部分，主要為透過體育課來進行問卷的填答，實際發出320份的問卷，回收總樣本為314份，剔除無效問卷，有效問卷為303份，回收率為98.1%，有效問卷率為96.5%。利用利用信度分析、項目檢定、二階段集群分析、單因子變異數分析、雪費爾檢定以及區別分析等統計方法進行分析。研究結果顯示運動行為、內在心理因素及社會支持越高對兒童身體質量指數有實際的影響並有差異存在。因此，希望能藉此研究提供給學校教師、家長於規劃及安排體適能相關活動及課程時的之參考。

Children obesity and it's related problems have become an epidemic disease and have raised significant attention from Governments throughout the world. The purpose of this study was to investigate how children's characteristics of sports participation influence the children's Body Mass Index. The children participants in this study were the students of the fifth and sixth grade enrolled in Taipei municipal elementary schools at the second semester in 2008. The survey was conducted in October 2008. 320 questionnaires were distributed and 314 questionnaires were returned of which 303 questionnaires were valid. -the valid rate was 96.5%. Reliability, item analysis, one-way ANOVA, Scheffe's, post hoc two-step cluster analysis, discriminant analysis was applied to data-analysis. In the study, it is proved that the internal psychological factors, social support and sports behaviors did make pronounced influence on primary school students' body mass index. Accordingly, results of this study would provide referable guidance to related parents and teachers when drawing up physical fitness related activities and courses in the future.