With China economic rapidly development, people’s living standard has been further improved, obesity problem is getting worse and worse, and obesity group in our country population also occupies more and more proportions. Study on our country population obesity and health has important significances in promoting our country people physical health development. Firstly, the paper starts from our country obesity problems, it studies obesity group development status, and obesity triggers a series of diseases, proposes that sports is a simple and most obvious effects lose weight way. Secondly, utilize variance analysis to study different sports to weight influential significances, it gets swimming has most remarkable influential effects on weight among jogging, sports dance, ball kinds of sports, swimming and other sports. On this basis, for swimming, it applies discriminant analysis to make further study, define best swimming time standard to adapt to lose weight and propose that best swimming time is 30~60min/ day, its losing weight effect is obvious, has bigger impacts on weight, waist circumference and other body shape, is one of most proper losing weight sports.