This study investigates experimentally the fuel bed width effect on concurrent flame spread over discrete fuels. Two representative configurations, dense arrays spaced 3 mm and loose arrays spaced 6 mm, are concerned herein. Regular birch rod arrays were designed by varying five kinds of column numbers (denoted by n, 3, 5, 7, 9, and 11) and five slopes (θ, 0, 15°, 30°, 45°, and 60°). Results show that flame spread rate (FSR) of dense arrays is lower than that of loose arrays. A predicted model of FSR is also developed, which is in good agreement with experimental results. Moreover, compared with the loose arrays, the decay of heat flux in the thermal plume region behind the pyrolysis zone is more rapid for dense arrays. For dense arrays, with increasing inclination angle, maximum convective heat flux, mass loss rate, and flame length decrease first and then increase at n > 5, but have an increasing tendency for loose arrays. Furthermore, the fuel consumption efficiency of loose arrays has an obvious superiority over dense arrays when θ > 15˚. In addition, dimensionless correlations between flame length and heat release rate are proposed both for dense and loose arrays.