The new generation mobile network 5G has become the main technology foundation in the architecture of the Internet of Things (IoT). In particular, millimeter wave communication technology in 5G is the core technology of the new generation network. Research on 5G networks faces many challenges in deploying real-life models to evaluate effectiveness. To resolve those issues, the article introduced the mmWave module integrated in the NS-3 network simulation toolkit to simulate and evaluate 5G network performance. The mmWave module is applied to simulate 5G network scenarios with the signal-to-noise ratio parameter SINR (Signal Interference + Noise Ration), thereby evaluating the wave quality from the base station to the terminal users to determine the most optimal location to build the base station.