A series of experiments to study merged flame from Multiple fire Sources was carried Out. The porous 15-cm(2) burner was used as a unit burner and propane was employed as a fuel. Many burners with Various heat release rates were placed in a square configuration with various separation distances. Flame height was measured using video images and temperature distribution with height was measured using thermocouples. The numerical results from the Fire Dynamics Simulator (FDS) of the National Institute of Standards and Technology was compared with the experimental data, and the comparison results show that FDS correctly simulates the merged flame from multiple fire sources. In addition, an empirical model to estimate the merged flame height was developed considering the effect of separation distance. The validity of this model was confirmed from the comparison with the simulation results, and excellent agreement is found between the calculated merged flame height from the model and the numerical ones. To study the detailed structure of merged flame, 3x3 fire source configuration was taken as an example to quantitatively show oxygen mass fraction profiles and velocity fields, which were also given to indicate the formation mechanism of the merged flame.