As the reform of the electricity market deepens, the integration of electric vehicles (EV) into the power grid can serve as a form of distributed energy storage, providing regulatory capabilities similar to battery energy storage. Exploring the potential of Electric Vehicle Aggregations (EVA) in participating in the ancillary services market can lead to a mutually beneficial outcome, achieving user benefits and ensuring the economic operation of the power grid. Building upon this, this paper proposes a framework and transaction process for simultaneous participation of multiple EVAs in the electricity and frequency regulation ancillary services markets. This framework is designed to meet user charging needs while establishing bid optimization strategies for the day-ahead market which take into account demand responsiveness and opportunity costs. This approach not only enhances user benefits but also improves the economic viability of EVA participation in ancillary services market regulation.