In order to ensure the security of important data during the construction of digital twin basin,this paper mainly focuses on the hidden risks of data theft,leakage,and damage faced by cracking massive high-precision data aggregation,and proposes a comprehensive protection plan for data security in digital twin basin based on network security foundation-data classifi cation and grading-data security protection. In view of the security vulnerabilities in data transmission,storage,and usage,a combining the point and surface encryption protection method combining full universal protection and application-level encryption is put forward,using commercial cryptographic techniques to protect data confi dentiality,integrity,and availability. This research method has been applied in important systems such as the map of national water conservancy,achieving a balance between data security and application effi ciency. Thus it can be widely applicable in water conservancy important data lifecycle protection of digital twin basin construction.