A multi-layer irregular reinforced concrete frame structure in the 8-degree area is taken as the research object, and the working principle and hysteretic model of the friction pendulum bearing (FPB) are explained in detail. With the help of SAP2000 finite element software, a friction pendulum isolation model and its corresponding non-isolation model were established. Plastic hinge constitutive models were defined at both ends of the beams and columns of the RC frame structure, and 100 sets of two-way elastoplastic time history analysis of ground motion are carried out by using dynamic time history method. The results show that: under rare earthquakes, the seismic response of interlayer displacement, interlayer shear, interlayer torque and interlayer torsion angle of the structure after friction pendulum isolation is significantly reduced. Among them, the maximum torsional angle of the base-isolated structure is reduced by nearly 60% compared to the maximum inter-layer torsional angle of the non-isolated structure, and the torque of the first-layer base-isolated structure is reduced by nearly 74.1% compared to the torque of the non-isolated structure, which can prevent serious torsional damage under rare earthquakes and ensure the safety of the structure.