For simulating the Pressurized Fluidized Bed Combustion (PFBC) start-up with high-temperature oil-fired gas, systematical experimental study and theoretical analyses were carried out on an Atmospheric Fluidized Bed Combustion (AFBC) test facility which has a water-cooled distributor in cross-section of 0.664 m x 0.656 m: The characteristics of heat transfer of the water-cooled distributor were revealed. The effects of some operating parameters on the normal start-up process are evaluated. The findings reported in this paper are used to provide a data base for designing PFBCB start-up systems. It can also be applied to the design of AFBC boilers and the improvement of existing ones.