Abstract: To study the effects of soil physical-parameters on soil anti-scourability in Yuanmou Dry – Hot Valley, soil particle size distribution, soil aggregate content, matric suction, cohesion c and friction angle φ of surface dry red soil were measured in Lab., and soil anti-scourability index (ANS)was determined by undisturbed soil trough scouring test in field. The results showed that the ANS and dispersion rate were the unary cubic multinomial change. ANS decreased gradually with the increase of dispersion rate. With the increase of the mean weight diameter MWD, ANS showed the power function growth. ANS also had the logarithmic function growth with the increase of matric suction, c and φ. The order of correlation degree between ANS and the different soil mechanical parameters were shear strength τf > φ> MWD>dispersion rate>matric suction>c. The stepwise regression analysis between ANS and the different parameters showed that ANS had good linear relation with cohesion c, mean weight diameter MWD and shear strength τf (multiple correlation coefficient R2=0.983). The partial correlation coefficient (R MWD(0.915)>Rc(0.829)> Rτf(0.776)) showed that the stability of water stable aggregate, the cohesive force between particles and aggregates and soil resistance to shear destructive power of flow had a great influence on ANS.