Abstract: By analyzing strict liability and fault liability ofeducational institutions，underage students and their guardians，we may find that the principle of fault liability is more profitable to the society in adjusting behaviors.In addition，the principle of fault presumption can lower the cost in judging the case，reduce the economic burden in identifying causal relationship，and decrease the cost of proof for the weak side.Therefore，according to the age of the underage students and their capacity for civil conduct，it is reasonable for the kindergartens，schools or other educational institutions to adopt the principle of fault liability and the principle of fault presumption in school sports injury accidents.

Key words: school sports injury accidents, liability principle, analysis from economics of law