Abstract: The present application relates to a quantum secure direct communication method and apparatus based on a one-way transmission, a device and a system. The transmitting terminal performs the error-correction anti-loss encoding on the to-be-transmitted message to obtain the code word corresponding to the to-be-transmitted message. The encryption key negotiated with the receiving terminal is adopted to encrypt the code word and the ciphertext message corresponding to the code word is obtained. Further, the ciphertext message is encoded onto the quantum state, and the obtained quantum state information is transmitted to the receiving terminal through the quantum channel.