Plane irregular buildings are prone to torsion and cause serious damage to the structure. The analysis and control of struc tural torsion effect is the key to this kind of structural design. In this regard， the simulation calculation of the planar irregular multi story frame model in the 8-degree fortification zone was carried out， and the planar L-type four-story frame isolation model of five typical class B buildings was established. The ratios of the length B and width W of the protruding limbs of the structure were set to be 1∶1，1.5∶1，2∶1，2.5∶1 and 3∶1， respectively. The dynamic characteristics and seismic response of different structures were ana lyzed. The influence of the LRB stiffness ratio and the rigid center position of the isolation layer on the structural torsion was dis cussed， and the effective control method of structural torsion was proposed. The results show that with the increase of the length width ratio B/W of the protruding limb， the X-direction torsion of the structure increases gradually， and the Y-direction torsion de creases gradually. Increasing the proportion of LRB stiffness can reduce the torsional effect of the structure. By comprehensively controlling the structural torsion and structural damping coefficient， a reasonable proportion of LRB stiffness can be obtained. The proportion of LRB stiffness of the isolation layer under the condition of 8 degrees earthquake is proposed. At the same time， the rig id center of the isolation layer and the rigid center of the superstructure are arranged on both sides of the mass center of the super structure to suppress the torsion of the superstructure of the plane irregular structure.