Objective To investigate the methods of controlling microorganism contamination and keeping clear in laboratory animal rooms of barrier system. Method To improve the air clearance methods of turbulent air flow in laboratory animal rooms of barrier system by setting non-dynamic facilities which can change the turbulent air flow modality in animal room into unidirectional way. Results In turbulent air rooms the average of bacterial sedimentation was 47, the floating bacteria was 154.5. In unidirectional air rooms the bacterial sedimentation was 1.5 and the floating bacteria was 7. Conclusion The unidirectional air flow is better than turbulent air flow. It will provide technical data for formulating new environmental standards of laboratory animal barrier system in future in our country.