This study examines the concept and application of surplus quota trading within the framework of water budget management. By comparing surplus quota trading and water rights trading

it analyzes key differences in traded volumes

transaction timing

underlying motivations

and procedural arrangements. Based on current regulatory requirements and the development status of China's water rights system

the paper proposes approaches for aligning the surplus quota trading mechanism with existing water rights trading systems. Taking Ningxia's water rights trading practice as a case study

it further explores the feasibility of incorporating surplus quota trading into regional water rights trading frameworks. The findings provide insights and practical guidance for establishing surplus quota trading mechanisms in pilot areas under water budget management.