Based on the characteristics of spatial structure of residential units, the effect of building space construction on temperature raise and hot smoke flow in residential fire was analyzed on building model with simulating multiple floors and rooms. The raise and distribution of temperature indoors were mainly tested under varied location of fire sources. And, the rule of smoke flow was discussed by using the law of temperature raise, indirectly. The results indicate that the mode of smoke flows is influenced by three spatial factors which include the form of junction terminal room construction; the height of down stand above the door and the relative locations of each room. The diffusion of hot smoke is prevented effectively by the down stand of the room; the temperature difference between indoor and outdoor should be higher than that of the room without down stand. When the open direction of door in non fire room is opposite to that of the door in fire room, there is much more hot smoke.