Abstract: For applying chemical measures to prevent projects soil and water loss, studying the effects of polyacrylamide (PAM) on soil erodibility and critical shear stresses of the red disturbed soil, stimulated rainfall experiments were conducted in the laboratory with 5 slope degrees as 5o, 10o, 15o, 20o, 25o and 3 rainfall intensities as 0.8 mm/min, 1.1 mm/min, 1.4 mm/min. The characteristics of the slope hydrodynamics parameters, relationships between runoff sediment transport rate and flow volume, variation of soil erodibility and critical shear stresses were analyzed with different soil treatments. The results showed that the sediment transport rate without PAM was 300 times larger than that with PAM when the runoff flow volumes were the same. The soil erodibility decreased from 13.223 g/(min·N) to 0.2693 g/(min·N), the runoff critical stresses increased from 0.77 N/(m2·min) to 1.47 N/(m2·min) with the application of PAM to the red soil. This means that the application of PAM can decrease the soil erodibility remarkably and increase the critical stresses. The results will provide theory basis for application of PAM to engineering soil and water loss prevention.