It is very important to obtain the distance between ventilation pipe outlet and tunnel face (short for the ventilation pipe distance) and the influencing laws of outlet volume of ventilation pipe on construction ventilation time. Hence, the minimum construction ventilation time of ventilation pipes with ventilation pipe distances of 1D, 2D, 3D and 4D, where D is equivalent diameter of tunnel crosssection, and 4 kinds of outlet volumes of 2 000 m3/min, 2 500 m3/min, 3 000 m3/min and 3 500 m3/min are studied by computational fluid dynamics (CFD) simulation, by taking mechanically constructed large crosssectional ZhenzhouWanzhou highspeed railway tunnel for example. The study results show that the construction ventilation time can be affected by ventilation pipe distance and outlet volume of ventilation pipe; the relationship between the construction ventilation time (t) and ventilation pipe distance (x) can be represented as t=ax2+bx+c, where a, b and c are functionally related to outlet volume of ventilation pipe (Q); the relationship among the construction ventilation time (t), ventilation pipe distance (x) and outlet volume of ventilation pipe (Q) can be represented as t=f(Q)x2+g(Q)x+h(Q), which is apply to the prediction of construction ventilation time of Xiangjiawan Tunnel. The study results are of great significance to theoretical guidance of determination of mechanized construction ventilation time of ZhengzhouWanzhou highspeed railway tunnel.