Abstract: The uncertainty of the combined incidence angle of seismic waves often has a significant effect on the dynamic response of faced rockfill DAMS. In this paper， the motion field of surface control points is decomposed by the principle of wave field superposition， and the time history of incident P and SV waves is obtained by two‑dimensional inversion. The angle of incident P wave and SV wave in the wave input model are randomly selected by the method of number theory. The influence of the uncertainty of combined incident angle on the seismic response of asphalt concrete faced rockfill dam is studied by the dynamic calculation of different combined incident angles. Taking a practical project as an example， by analyzing the mean value， coefficient of variation， 95% confidence interval limit and extreme value difference of the horizontal peak acceleration of foundation surface， panel stress and acceleration， dam body horizontal peak acceleration and permanent deformation， and other statistical laws and distribution type tests， and compared with the vertical incidence of seismic waves， The influence of random combination incidence Angle and input ground motion intensity on random response dispersion degree and obedience probability distribution is analyzed. The results show that considering the uncertainty of the combined incidence angle， the seismic response dispersion of the foundation surface of the dam will increase. The maximum principal tensile stress of the panel increases by at least 40% compared with the calculated result of vertical incidence. The influence of the horizontal peak acceleration on the dam crest and the panel crest is greater than that on the permanent deformation. Compared with the results of vertical incidence， the permanent deformation of the three groups of seismic waves has a transcendental probability of more than 70%. The statistical results of seismic response of dam body may not accord with normal distribution. The dispersion of seismic response results of overlay layer is greater than that of dam body.