Although wider application of steel-plate composite (SC) walls has been seen in recent years, the investigation on the L-joints composed of SC walls is still limited. This paper focused on the seismic behavior of L-joints, where the large scale tests and numerical study were carried out. The test observations, failure modes, load-carrying capacities, load–displacement curves and load vs. strain curves of the six test specimens were reported and analyzed in detail. The benchmark finite element (FE) models to simulate the behavior of test specimens were established using ABAQUS. The parametric study including 68 models was conducted based on the benchmarked FE models. The critical parameters in the current equations for calculating the joint shear force and joint shear strength were calibrated using the FE and test results. The code equations for the flexural strength of SC wall were also evaluated by the data of the specimens with flexural failure of SC wall in the parametric study.