As semiconductor devices become smaller and smaller, device aging simulation plays an increasingly important role in the overall circuit design. In recent years, the research of device aging modeling has gradually become the focus of researchers. Most of the current aging modeling methods only consider the degradation of one parameter, resulting in inaccurate simulation of the model in actual testing. In response to this problem, this paper establishes an HCI(Hot Carrier Injection) aging model on NMOS devices, focusing on the simultaneous degradation of multiple parameters (drain current in saturation region $(I_{dsat})$ and threshold voltage $(v_{th})$ in the process of extracting model parameters. Simulation results show that this method can improve the fitting accuracy of aging model.