Based on the lightweight steel-concrete framework system of modular wall structures， this study proposed a lightweight steel-concrete composite column-H-shaped steel beam joint suitable for this system. In order to study the mechanical properties of this joint， monotonic loading tests were carried out on three groups of beam-column joint specimens. The experimental results indicate that under monotonic loading at the beam end， the joint exhibits distinct semi-rigidity characteristics. The failure is characterized by yielding deformation of the flange of the combined steel column and concrete cracking， ultimately leading to joint failure due to excessive bending deformation of the top angle steel and the cracking of the stiffener weld. A refined simulation was conducted using ABAQUS finite element software. The deformation process and failure characteristics of the finite element model agree with the experimental results. The researchers consider three key parameters， namely， the height of the H-shaped steel beam section， the thickness of the C-shaped steel， and the thickness of the angle steel， a parametric analysis was performed. The results indicate that increasing the beam section height and the thickness of the angle steel connector significantly enhances the joint's flexural load-carrying capacity and initial rotational stiffness. In contrast， increasing the thickness of the C-shaped steel has a limited impact on the joint's flexural load-carrying capacity， with a minor effect on the initial rotational stiffness.