Uniform distribution at the channel and pipe is an important factor affecting not only floc formation of flocculation basin but also precipitation efficiency of sedimentation basin. There are a variety of design factors at the distribution channel such as the open channel type, pressure pipe type, velocity of channel inside, structure of inlet, outlet size, etc. we evaluated most suitable design method of the distribution channel of the flocculation basin by using computational fluid dynamics in this research. First, the uniformity of distribution is improved when the ratio of channel inlet and outlet Cross-sectional area small. If, however, the ratio of Cross-sectional area is become small, pressure in the channel rises. So the basis of the uniformity and pressure in channel, the suitable ratio of Cross-sectional area is about 5%~10%. Second, in the uniformity of distribution, the pressure pipe type is excellent than the open channel type. Third, the suitable inlet velocity of water is about o.5m/sec if consider the prevent sedimentation of SS and the rise of pipe pressure. Fourth, we can improve the stability of water flow by increasing the length of the inlet section, therefore proper inlet length is about 5m.