The invention provides a low voltage transformer area anti-electricity-stealing diagnosis system. A data information acquisition unit sends acquired data information to a data storage unit for storing the acquired data information. A data processing unit calls ammeter data and encryption information stored in the data storage unit. The ammeter data are encrypted according to the set encryption information and are uploaded to a monitoring center according to a set protocol by a data communication unit. The data processing module screens and arranges the ammeter data, carries out analysis, statistics and storage of power utilization information, and carries out contrast analysis between the collected power utilization information and that of a former acquisition period. The system can carry out encryption and decryption communication of the ammeter data, can directly extract an encryption object or decryption object for carrying out encryption or decryption, ensures the safety of the ammeter data, and prevents other people from stealing ammeter information. The encryption and decryption efficiency and the success rate of data are raised, so that the usage experience of the user is improved.