The commercial software CFD with code CFX was used to simulate the flow and mixing characteristic of shear thinning liquid in a Φ 480 mm agitating tank with two 45° pitch of paddles and without baffles, including the simulation of the height of free-surface and movement time of tracer-particle in free-surface. VOF,Lagrangian particle tracking and laminar flow model were used, and the result was compared to experiment result.The simulation results can give some useful information for the design of industrial agitating tank.