Due to the difficulty of conserving the water and soil of the hillside land in the catchment basin Area, it tends to produce high-turbidity raw water during the initial period of typhoons or storms and affect the operation of the Purifying System. In this Research, the raw water presenting varied turbidity levels was sampled from different depths under the water surface to simulate the change of the water quality. During the research, a Barrier Board was used to extend the flowing route and the level change of the overflow; further, varied flow rates were also employed to carry out the pre-treatment of high-turbidity raw water in order to study the changes of particle size of the influent and effluent water. In respect to Particle Size Analysis, the Particle Size (D<sub>98</sub>) of the High-turbidity Raw Water was roughly between 100~125μm; after the pre-treatment with the Barrier Board, the Particle Size at ＜D<sub>10</sub> was between 0.73~2.13μm. With the increase of accumulated particle size percentage, the effluent water was able to reach <25μm at D<sub>98</sub> of Particle Size under the low rate (8ml/s), the effluent water D<sub>98</sub> was able to reach <10μm, which is an outstanding removal effect. In view of this, a certain degree of effect could be achieved by treating the High-turbidity Raw Water before it settles.