In order to ensure the reliability of drugs, long-term experiment on the food security, and pathological results, the requirements of laboratory animals in clean environment in breeding. From the point of view of controlling microorganism, the laboratory of medicine and biology can be divided into four levels and three kinds. ABSL-1, ABSL-2, ABSL-3, ABSL-4, said the corresponding level of animal biological safety laboratory. ABSL-2, ABSL-1 is the basic laboratory, ABSL-3 is the protection laboratory, ABSL-4 is the advanced protection laboratory; ABSL-1 level requirements are relatively low, ABSL-4 requirements are the highest. The ABSL-4 can be divided into safety cabinet type, pressure type and mixed type three. Two biological safety laboratory implementation of a barrier or two barrier, three, four biological safety laboratory at the same time the implementation of a barrier or two barrier. There are different requirements at all levels of barrier parameters to two barrier for example, technical index of four grades: Grade a laboratory cleanliness is not required, the minimum number is not required, you can open the window, and communicated with the adjacent outdoor room minimum negative pressure difference is not required, the temperature is 18 to 28 DEG C, relative humidity is less than 78%. The noise is less than or equal to 60dB, minimum illumination 200; two level of cleanliness is not required, the minimum number is not required, you can open the window, and communicated with the adjacent outdoor room minimum negative pressure difference is not required, the temperature is 18 to 27 DEG C, relative humidity 30 ~ 60%, the noise is less than or equal to 60dB, minimum illumination 300; three level of cleanliness of 7 or 8. The minimum number of 15 or 12, and communicated with the adjacent outdoor room minimum negative pressure -10, temperature 18 ~ 25 degrees, relative humidity 30 ~ 60%, the noise is less than or equal to 60dB, minimum illumination 350; four level of cleanliness of 7 or 8, the minimum ventilation frequency of 15 or 12, and the adjacent phase Through outdoor room minimum negative pressure -10, temperature 18 ~ 24 degrees, relative humidity 30 ~ 60%, the noise is less than or equal to 60dB, minimum illumination 350LUX