A modified Particle Image Velocimetry (PIV) was developed in this work with simplified data acquisition and image processing system. The modified PIV could be used for measurement of the flow field in a big size tank with poor transparence fluid. Experiments were carried out in a baffled stirred tank of 0 5 m diameter filled with 0 6%CMC aqueous solution and water respectively. The flow field generated respectively by a 45°pitched blade turbine (PBT) and a 2 blade CBY was measured by using the modified ...