The number of devices and users in the Internet of Things environment may be very large and constantly changing, and the system needs to be able to adapt to this dynamism and support rapid expansion. To this end, design an IoT private data access control system based on ciphertext attributes. The system consists of a client module, a server module, and a key generation module. The client module is mainly responsible for data reception, encryption, key management, and decryption; The server module generates partial key components through attribute based encryption algorithm. By binding access permissions to ciphertext attributes, the system can achieve more refined access control, ensuring that only users or devices that meet specific attributes can access data. Obtain the data master key through re encryption and store the data key in the data management repository; The key generation module is responsible for maintaining key components and data attribute sets, ensuring that the data attribute list is updated in a timely manner when users cancel or add access, enabling the system to quickly adapt to new users and devices and support system expansion. Finally, the decryption server decrypts the key and outputs plaintext, achieving access control to private data in the Internet of Things environment. The system test results show that the system can encrypt and store private data of the Internet of Things within 30ms, with an encryption strength of up to 95%. The frequency histogram of the encrypted Internet of Things data fluctuates very little, and the access success rate is very high, ensuring the safe and stable operation of the Internet of Things system.