This paper investigates fractal property changes of pore structures during coal devolatilization. Similar to char pores, coal pores can also be classified as micro pores and macro pores based on their fractal dimensions. The specific surface area and fractal dimension of micro pores in coal particles are basically unchanged after devolatilization. However, the specific surface area and fractal dimension of macro pores, which are key factors in char combustion, are increased after devolatilization. In fact, the fractal dimensions are basically doubled. These parameters will affect another fractal geometrical factor β in char pores that is correlated to char combustion rate. Since the rate of char combustion can be predicted from their fractal pore properties, it may be possible to predict char combustion directly from the properties of their parent coal pores in the future.