Abstract: With the fast development of nuclear power industry in China, it is inevitable to encounter non-rock site during site selection. Focusing on the seismic response of the nuclear island in non-bedrock site under oblique incidence, a three-dimensional finite element model for the soil-structure system including the CAP1400 nuclear island structure and near-field rock site is established. Based on the viscous-spring artificial boundary and oblique incident ground motion input method, the influence of oblique incident angle of P-wave and non-rock layered site on the seismic response of the nuclear island is studied. Research shows that non-bedrock site will increase the acceleration response of the nuclear island structure and its floor response spectrum, and in most conditions will also increase the relative floor displacement; As the incident angle of P wave increases, the nuclear island structural vertical response decreases, the horizontal response increases, and the spectral characteristics of the floor response spectrum will change.