Abstract: The heart rate variability(HRV)signal contains a lot of information,such as the control of cardiovascular system and the regulation of body fluid.It can be used to analyze the balance of sympathetic nerve and vagus nerve.From the perspective of autonomic nervous system(ANS)balancing,the process of physical exercise is the destruction of the former balance and the formation of new balance of ANS.If the ANS is in state of imbalance or unactivity for a long time,it will lead to a decrease in the effect of exercise,increase the risk of exercise,even endanger the health.The effect of exercise intensity on HRV is obvious,the main line of this paper is the intensity of exercise and the change of HRV after different intensity of exercise and strength training.At present,the results of research on HRV is not consistent,which is mainly due to the influence of age,gender,health level,exercise intensity,test method and so on.In this paper,the application of HRV in fields of the mass fitness is proposed,and it is recommended to carry out longitudinal follow-up tests.In order to make better use of HRV,it is necessary to evaluate the adaption of the individuals to different exercise.