Nonlinear behavior is often observed in structural joint system due to external loads. A new technique of nonlinear structural joint model updating with static load test results is proposed in this article to investigate the actual behavior of a joint system. To calibrate the nonlinear parameters of the structural joint system, an appropriate finite element model is first established to characterize the complex nonlinear behavior caused by the joint connections. Combined with the sensitivity analysis, the parameters that describe the nonlinear behavior of the joint connections are selected as the parameters to be updated. Subsequently, an objective function is created in accordance with the residual between experimentally measured static deflections and analytically calculated static deflections through finite element model. The objective function is then optimized to obtain the proper values of the nonlinear force-displacement parameters with the regular simulated annealing algorithm. To validate the efficiency of this updating approach, two numerical examples under static concentrated loads are conducted. The obtained results indicate that the nonlinear joint model parameters can be successfully updated, and the updated new model can further forecast the true deflections of the nonlinear structure with good accuracy and stability.