Based on the purpose of protecting the interests of the disadvantaged minority,lawrequires operators to shoulder a wide range of responsibilities of security;but operators are not the insurers of all the risks of consumers,namely,operators only shoulder corresponding responsibilities for holders of rights as to the responsibilities of security within reasonable limits."Reasonable limits"is an abstract concept,the detailed regulations or explanations of which hasn't been made legally.The article suggests,confronting So complex law cases,that defining operators'"reasonable limits"of security responsibilities should be analyzed from the two perspectives of practice and theory together with actual law cases.