The granular sludge mentioned this paper in the 1m diameter stirred tank contains 92%(w) water and 0.01 m diameter solid granule. The numerical simulations of mixing processes of sludge and solid granule in the stirred tanks equipped with six shifted blades propeller (6SBP) and six blades propeller (6BP) were conducted respectively by using Fluent software. The numerical analysis of the concentration field distributions, the mixing times and the mixing energy per unit volume under the above two different propellers were carried out according to the simulation results, and the particles concentration distribution was demonstrated by experiment. The results show: the simulation curves of particles concentration distribution consists with the experimental one well. The mixing process is closely related to the flow pattern, and the concentration field distribution with shifted stirring blades tends to be stable faster. The 6SBP exhibits high perfomance in terms of mixing efficiency, the mixing time of six shifted blades propeller is 27 s at agitation speed of 4 r/s, while it costs 6BP 9 s more under the same condition. And the mixing energy per unit volume by six shifted blades propeller is only 79.6% of that by normal propeller.