The influences of layout and amount of ventilation openings on ventilation effects of multipleramp highway tunnel in urban areas, such as concentration of pollutant and ventilation efficiency of openings, are analyzed by ventilation simulation software SES (subway environment simulation). The analytical results show that: 1) The concentration of pollutant in tunnel and at tunnel exit can be effectively reduced by setting ventilation openings on tunnel roof. 2) Good ventilation effect will be reached by setting centralized openings above fork of ramps, which will result in a reduction of construction cost. 3) Ventilation openings should be increased especially at back section of tunnel when the tunnel section between two forks is too to meet ventilation standards.