Abstract: Fractal theory has been introduced into heterogeneous reaction systems to describe the reaction of solid particles with fluid, and a fractal reaction model in two dimensions is proposed for irregular particles. Based on the characterization of irregular particle shape, the reaction time which are determined and controlled by fluid film diffusion, ash diffusion and chemical reaction are theoretically analyzed. A pseudosteady-state equation of material balance and its solution as the concentration profile of reacting fluid are given for the shrinking-core model for irregular particles with constant radii. Meanwhile, some parameters related to reaction time complete reaction time, relative reaction time and the amount of reacting fluid per unit time, are also expressed with fractal dimension and shape coefficient. The results indicate that the higher the fractal dimension, the higher the total reaction rate, and the shape coefficient also influences the reaction time.