When designing and constructing the refuge chambers, it was quite urgent and necessary to solve how to effectively use the compressed-air self-help system to supply sufficient oxygen for people. The calculation of air supply tube diameter and air discharge tube diameter was import to protect safety for people in the refuge chambers. Firstly, According to the air quantity for the refuge chambers, the air supply tube diameter was studied. Secondly, according to the analysis of the most pressure to body, the overpressure in the refuge chambers was studied. Thirdly, base on the fluid mechanics theory, the diameter of discharge air tube was studied. Last, the absolute pressure was calculated to check if the person in refuge mchambers was safe. The results provide a more reasonable way for refuge chamber design.