Abstract: In recent years, the increasing frequency of extreme weather events and the accelerated progress of "new electrification" on the demand side have led to dual challenges: a sharp rise in the risk of short-term supply-demand imbalances within power systems and a lack of sufficient flexibility resource regulation margins. To fully exploit the market value and regulatory potential of large-scale electric vehicles (EVs) on the demand side, we propose a multi-stage hierarchical electricity market-oriented Stackelberg game-based pricing strategy for electric vehicle aggregators (EVAs). First, the power and energy schedulable boundaries of EV clusters are quantified based on the charging-travel characteristic distributions of individual EV. Second, a comprehensive user utility function is constructed to characterize the differentiated responses of EV users to electricity price sensitivity and charging comfort preferences. Finally, a leader-follower Stackelberg game optimization model is developed, where the EVA acts as the leader and EVs as followers. This model enables their participation in multi-stage interactions across day-ahead energy markets, frequency regulation markets, and demand response markets. Case studies demonstrate that the proposed method effectively maximizes the benefits of both EVA and EV, while meeting the regulation requirements of demand response markets. Furthermore, the impacts of demand response market subsidy pricing and user consumption preferences on EVA revenue and EV charging costs are quantified, providing insights for EVAs and EVs to address different regulatory demand scenarios.