The jet ventilation of Mingtangshan Twolane Road Tunnel is numerically simulated so as to optimize the spatial layout of ventilation fans; and then the factors for the pressure rise of ventilation fan, i.e. longitudinal distance among fans, setting height of fan and transverse distance among fans, are discussed. The authors suggest that the jet fans should be installed at the position higher than building boundary about 15-30 cm； the transverse distance among fans should be 1.5-2 times fan diameter； and the longitudinal distance among fans should be larger than 150 m. The computational fluid dynamics (CFD) simulation results show that the jet ventilation fan after optimization can achieve good effect.