In dense granular flows, a non-local rheology theory was proposed by Pouliquen et al. based on the idea of a self-activated process, in which a rearrangement at one position will be trigged by stress fluctuation due to rearrangements elsewhere in the material. Taking into account the probability density distribution of stress fluctuation amplitude in granular materials and the coupling effect between shear rate and volume fraction in iterative calculation, a modified non-local rheological model was proposed...