By the revision of the Building Standard Law, to ascertain the evacuation safety performance, the methodology that regards a fire as the phenomenon of combusion that the heat release rate changes every moment was added. The purpose of this paper is to consider the influence of the characteristic of fire load on the heat release rate and smoke movement at the early stage of the fire. First, we estimated the heat release rate and smoke movement in the room where fire started by changing some parameters with the model that considered the random distribution of fire load, and inspected the limited time defined as an indicator of fire safety, that occupants in the room where fire started could safely evacuate. Second, we examined about the limited time by changing smoke exhaust rate in the same way.