Natural convection in a cubic inclined enclosure with three isolated plates was investigated experimentally. The influences of the plates' spacing, the inclination angles of the enclosure, and the Rayleigh number on the heat transfer of the plate group were obtained. It was found that under a fixed Rayleigh number, there is a plate spacing at which the heat transfer rate of the three plates is approximately the same for the horizontal plate group. Under the range of Rayleigh numbers considered, the heat transfer rate of the plate group is less than that of the natural convection of the plate group in infinite space. The heat transfer rate of the plates increases with the plate inclined angle tilting from θ=90 deg to θ=0 deg, with the most steep increase occurring in the range of θ=90 deg to 45 deg. A global correlation of the heat transfer results for all the inclination between 0 deg and 60 deg can be obtained as Nul,m=0.5360 (Ra1cos) 0.25 with a spread of ±8.9 percent.