This article presents a numerical study of combustion of low-calorific-producer-gas from Mangium wood within a late mixing porous burner (LMPB). The LMPB consists of four main components, i.e., the fuel preheating porous (FP), the porous combustor (PC), the air jacket, and the mixing chamber. Interestingly, this LMPB was able to highly preheated and it still maintained high safety in operation. A single-step global reaction, steady state approach and a one-dimensional model were considered. The necessary information for burner characteristics, i.e., temperature profile, flame location and maximum temperature were also presented. The results indicated that stable combustion of a low-calorific-producer-gas within LMPB was possible achieved. Increasing equivalence ratio resulted in increasing in the flame temperature. Meanwhile, increasing the firing rate caused slightly decrease in flame temperature. The flame moved to downstream zone of the PC when the firing rate increased. Finally, it was found that the equivalence ratio did not affect the flame location.