The current study, related to the flow rate variation and the combustion feed, which were analyzed during combustion process in fluidized bed combustor at University of Indonesia. The air supplies used for this experiment were 0.085 and 0.095 m3/s. Both of air supply used with coconut shell as the biofuel, was applied to find correlation between the time and the fuel needed to achieve the self-sustaining combustion state. After the self-sustaining combustion achieved, the feed rate and its effect for the temperature are analyzed. It was found that the experiment with higher air supply gave higher output temperature in the freeboard area.