Abstract: A fully homomorphic encryption method based on modular operation, the method including: acquiring a plaintext of any numerical value data type in an encryption process and converting the plaintext to a corresponding plaintext system plaintext according to an encryption requirement; performing an encryption operation on each number in the system plaintext, and combining ciphertexts acquired by the encryption operation to obtain a corresponding ciphertext combination; performing a ciphertext operation on the ciphertext combination using a ciphertext source code, a ciphertext radix-minus-one complement, and a ciphertext complement code based on modular encryption; and using modular division to decrypt a result of the ciphertext operation to obtain a decrypted plaintext.