In this paper, simulating a group fire in a densely inhabited area with weak small wooden buildings, we performed reduced scale model experiments to investigate flame merging. To study this phenomenon, a lot of experiments were performed using crib and liquid fuel. In this work, however two or more square propane porous burners are used, and the flame height, heat flux, and temperature distribution on the center axis of fires are measured. Consequently, the influence of the heat release rate, the number of fire sources and the distance between fire sources upon flame merging has been investigated. It is found that each of those parameters affected flame merging, although the number of fire sources seemed to be the most important parameter.