In the automotive industry, there is a growing demand for one-sided joining of dissimilar materials for efficient fastening process and light weight vehicle. The finite element simulation of an automobile using such a joining technology with 3D elements leads to an unrealistic computational cost due to the geometrical structure of the joining connections and complexity of the model. For efficient simulation, it is essential to use a shell element and a simplified connector model. Here, to model a simplified connector model of one-sided joining of dissimilar materials, we used a simplified connector model which is developed for self-piercing rivet. We analyzed parameters which describe the behavior of simplified connector model and parameters were determined using optimization. The lap shear and cross tension simulations of simplified connector model was validated with the experimental results.