The purpose of this study was to investigate the relationships among shoulder isokinetic strength on 50M sprint time (50ST), propulsive power of arm stroke (ASP), and whole stroke (WSP) in front crawl swimming. Twenty-two male swimmers (age=19.3 ± 2.1yrs, Ht=172.6 ± 4.6cm, Wt=68.3 ± 7.9kg), voluntarily participated in this test. By using MERAC dynamometer, we tested subjects' internal and external rotation of isokinetic power and strength. statistical analyses indicated that there were significant (p<.05) relationships between 50ST and propulsive power of ASP and WSP, including internal rotation of isokinetic power and strength. The best variable to predict 50ST equation was 35.1701120-182685 (internal rotation of isokinetic strength at the speed of 300 deg/s) -0.234561 (propulsive power of WSP) (R2=.75,P<0.05). Conclusions:Internal rotation of isokinetic strength and propulsive power training may be a useful method to improve swimmers' speed.