The mechanical ventilation smoke management system involves the use of Supply Fan, jet Fan, and exhaust Fans, which are activated at different times after a fire is extinguished. This paper numerically investigates the effect of the priority and delay of smoke management systems on smoke distribution and visibility in a car park after a fire, using Fire Dynamic Simulation Code 6.7.6. The flow rates of the exhaust Fan, Supply Fan and jet Fan are 1.9 m³/s, 1.43 m³/s, and 1.67 m³/s, respectively. The fire, located near the Supply Fans, is modeled as a rectangle with dimensions of 2.0 × 0.8 m² and a power of 1.6 MW, lasting for one minute from ignition to extinguishment. Polyurethane is assumed as the flammable material. The priority and delay of the smoke management systems are evaluated through four scenarios over a period of 420 seconds. The results show that visibility reaches acceptable levels in all scenarios at all locations after 420 seconds. Additionally, the results indicate that the visibility of the upper half is highest for scenario a, at around 15 m. However, the visibility of the lower half is highest for scenario d, ranging between 20 and 30 m. It can be concluded that delaying the activation of smoke management systems is an effective strategy for facilitating smoke removal and fresh air intake.