Objective To study the dynamic situation of germ about laboratory animals'barrier system.Methods Using cotton pledget to test the concentration of bacteria in different area of barrier system,as well as through the method of airfall bacteria.Results The results showed that in dynamic enviroment,especially in animal laboratory rooms,the airfall bacteria was far more than static condition which has been limited below 3cfu/dish in the National Standards for Laboratory Animal Environment and Facility(GB14925-20...