Vehicle-to-grid (V2G) network, which provides electricity charging service to the electric vehicles (EVs), is an essential part of the smart grid (SG). It can not only effectively reduce the greenhouse gas emission but also significantly enhance the efficiency of the power grid. Due to the limitation of the local electricity resource, the quality of charging service can be hardly guaranteed for every EV in V2G network. To this end, the multi-quality charging is introduced to provide quality-guaranteed service (QGS) to the qualified EVs and best effort service (BES) to the other EVs. To perform the multi-quality charging, the evaluation on the EV's attributes is necessary to determine which level of charging service can be offered to the EV. However, the EV owner's privacy such as real identity, lifestyle, location, and sensitive information in the attributes may be violated during the evaluation and authentication. In this thesis, a privacy-preserving multi-quality charging (PMQC) scheme for V2G network is proposed to evaluate the EV's attributes, authenticate its service eligibility and generate its bill without revealing the EV's private information. Specifically, by adopting ciphertext-policy attribute based encryption (CP-ABE), the EV can be evaluated to have proper charging service without disclosing its attribute privacy. By utilizing group signature, the EV's real identity is kept confidential during the authentication and the bill generation. By hiding the EV's real identity, the EV owner's lifestyle privacy and location privacy are also preserved. Security analysis demonstrates that PMQC can achieve the EV's privacy preservation, fine-grained access control on the EVs for QGS, traceability of the EV's real identity and secure revocation on the EV's service eligibility. Performance evaluation result shows that PMQC can achieve higher efficiency in authentication and verification compared with other schemes in terms of computation overhead. Based on PMQC, the EV's computation overhead and storage overhead can be further reduced in the extended privacy-preserving multi-quality charging (ePMQC) scheme.