Journal of Electronic Systems Bo Zhou, Chao Zhou 6 4 2016 http://www.dline.info/jes/fulltext/v6n4/jesv6n4_3.pdf The physical activities are helpful for the health of teenagers as it can strengthen constitution and bone health and lower risks of cardiovascular disease and metabolic disease. Actigraph sensor can more accurately evaluate energy expenditure of teenagers during physical activities. This study observes and researches energy expenditure indexes of human body in physical activities combining Actigraph sensor, in order to provide a basis for studying the relationship between physical activities and health.