This research explores how Vehicle-to-grid (V2G), which helps facilitate load elasticity for EV charging, contributes to demand response in power grid. The analysis includes the worldwide case studies of V2G, the forecasts of energy consumption of EVs, and the peak shaving effect of V2G on power system. The result shows that the introduction of V2G and smart charging in the evening is effective in smoothing the load curve, shaving the electricity consumption by 20% compared to business-as-usual scenario, which could be a solid referral for the relevant policies.