To research how vertical joints effect the seismic performance of prefabricated L-shaped shear wall, three L-shaped shear walls with shear span ratio of 2.15 were studied experimentally by the quasi-static test system. The vertical joints which are in different positions in two prefabricated wall are unreinforced keyway, and the other one is cast-in place. The test results show that the crack pattern has some difference with cast-in place shear wall. Cracks will go not cross the vertical joints directly, but crossing the vertical joints from its shear key shape point. The vertical joints have little effect on horizontal bearing capacity and failure modes, but ductility and energy dissipation are influenced significantly. The forward displacement ductility of two L-shaped wall with vertical joints increase by 0.2% and 14% repectively while the backward displacement ductility increases by 8% and 14%, and energy dissipation capacity increases by 30%. The position of vertical joints has little effect on energy dissipation. In addition, there were no sudden increase of strain and yield in advance in horizontal reinforcement crossing the vertical joints.