Swimming is one of modern people favorite indoors events after work, meanwhile it is also Olympic Games important competition event. To improve men’s 100m freestyle swimming level, the paper uses grey GM (1, 1) prediction model, establishes performance prediction model, and makes prediction on Chinese men’s 100m freestyle performance in the 31st Olympic Games. Make use of grey prediction to make correlation analysis of performance development influence factors. And establish differential equation model by analyzing original data, it gets performance development trend status. And it further gets that Chinese men’s 100m freestyle will get result as 47.92s in the 31st Olympic Games. By prediction men’s 100m freestyle performance, it analyzes Chinese men’s swimming performance development trend, it finds that Chinese and other swimming powers gap is still very big. Chinese athlete development still keeps larger paces with human body extremity, which still needs to increase athlete daily training’s intensity of training.