Fire　safety　is　a　key　issue　for　an　underground　car　park　with　flat　and　restricted　space.　Based　on　the　experimental　results,　effect　of　smoke　exhaust　assisted　by　jet　fans　has　been　investigated　in　the　underground　car　park　by　numerical　simulation.　The　influence　of　jet　fan　layout　and　outlet　velocity　on　smoke　temperature　and　visibility　is　discussed.　Results　show　that　the　use　of　jet　fans　to　assist　smoke　exhaust　can　effectively　control　smoke　diffusion　in　an　underground　car　park.　The　arrangement　of　twenty　fans　with　outlet　velocity　of　8m/s　can　accelerate　the　extraction　of　smoke.　©　2019　IEEE.