Abstract: In the past 40 years of reform and opening up, China's youth physical health policy has undergone four stages: adjustment and recovery (1979-1986) , perfection and standardization (1987-1996) , reform and deepening (1997-2006) , top-level design and collaborative innovation (2007-2017) , which make China's youth physical health policy gradually improve and become perfect. However, the results of the physical fitness test of Chinese students show that the physical health of Chinese youth is still facing a severe situation. Based on the Smith policy implementation system model, we reflect on the Chinese youth physical health policy and find that: 1) The inherent limitations of policy lead to the target deviation, value shift and effect bias; 2) The imperfect implementation mechanism leads to poor coordination, insufficient motivation and inadequate supervision; 3) The self-interest of the target group's interest choice leads to insufficient policy identification, deviation from direction and low effectiveness; 4) The changes of examination-oriented education system and modern life style lead to the weak environment for policy implementation. In order to further improve China's youth physical health policy and improve the effectiveness of policy implementation, the following suggestions are proposed: 1) Establish China youth physical health strategy committee and overall plan the youth physical health policy system; 2) Create a cross-border, linkage and efficient policy implementation mechanism and expand policy implementation resources; 3) Improve the policy performance appraisal mechanism and strengthen the supervision of policy implementation; 4) Improve the policy identification of target groups and optimize the policy implementation environment.