To explore velocity distribution of turbulent flow in rectangular channel under the influence of sidewall, the comparison and analysis of the main formula of velocity distribution which are applicable to rectangular channel in current were presented and the advantages and disadvantages were listed.The parabolic distribution was selected which reflects vertical velocity distribution near sidewall well.According to the three-dimensional Reynolds equation,a model of mathematical physics on turbulence was created. Cross-sectional velocity distribution formula and average velocity transverse distribution formula under the influence of side-wall were deduced.Ify/h>0.2,the relative error between measured value and calculated value is less than or equal to 3% in channel central region,and the relative error is at about 6% in side-wall region.Ify/h
