Ring signature schemes are being used in many scenarios that require both accreditation and privacy of the user’s identity. For example, ring confidential transaction protocol in Monero uses ring signature as an underlying scheme. Almost all ring signatures deployed in practice are based on number-theoretic assumptions which are vulnerable to quantum computers. Existing efficient ring signature schemes rely on NTRU lattices or structured lattices which are more susceptible to attacks than generic lattices. We propose a new generic construction of ring signature based on generic lattices and give an instantiation called Lion, which has the best security and strikes the best balance between computational efficiency and storage overheads. Compared with Raptor, which is almost as practical as number-theoretic-based ring signatures, Lion has comparable computational efficiency and smaller signature size(roughly 1.07KB per user). Based on standard hardness assumptions, Lion follows the strongest security definitions of ring signature in random oracle model. In addition, Lion does not need to rely on trusted third parties.