Abstract: Environmental protection is an important issue of the constitution. Article 26 of the constitution belongs to a special provisions,which should be placed on a particular theoretical framework to explain.Germany"system security"theory can refer to the basis for the interpretation,according to this theory,the protection effect is"core irrevocable,edge can limit".Modern institutional safeguard belongs to the objective value order,the state must be"actively shape the system".The environment as a system,guaranteed by the Constitution.Through the institutional safeguard which has the negative and positive dual structure,the constitution imposed a state obligation to implement environmental protection.