Abstract: Objective:To examine the feasibility and validation of critical velocity(CV)in elite swimmers by using competition data,and to investigate the effect of year-on-year's CV variation on the year-on-year's performance in elite middle-and longdistance swimmers. The logistic regression model was developed based on variation of year-on-year's CV to predict incidence probability for the variation on the time of elite long-distance freestylers. Methods:The results of the top 100 world swimmers from 200 m to 1 500 m freestyle events during 2011 to 2018 were collected. CV were calculated by using distance-time model,and the relationships between performance time and CV in middle-and long-distance freestylers were examined. The effect of year-on-year's CV variation on the year-on-year's performance time variation in middle-and long-distance freestyle was evaluated by logistic regression model.Results:76.8%,87.2%,90.7% and 99.5% variation of performance for 200 m,400 m,800 m and 1 500 m freestyle events can be explained by CV respectively. With increasing CV,swimmers who have improved their longdistance freestyle(800 m and 1 500 m)performance showed 30 times odds ratio more than those who have not improved their CV.When CV was increased or decreased 1%~6% yearly,the probability of performance increase or decrease in long distance freestyle will reach to 80%~100%. Conclusion:The feasibility and validation of CV by calculating from competition data is acceptable. The performance variation of year-on-year's CV percentage is a key factor to explain the performance variation of year-on-year's long-distance freestyle events.