Abstract: Compressed air system provides compressed air what the whole nuclear power plant needed, and needs to meet the operation and Maintenance of the power facilities of all plant. With the experience during debugging of the compressed air system of Fangjiashan Nuclear practical, demonstrated the Reliability of the overall design of the system in terms of supply capacity of the system, isolate control and packing capacity at accident conditions; At the same time it has made a number of field-proven reasonably practical measures.