In order to improve the communication efficiency and security of quantum secure direct communication proposed by Chang Yan etal, a quantum secure direct communication scheme based on d-dimensional Bell entangled state is designed. Before communication, the unitary transformation is carried out on d-dimensional Bell-state particles by the sender Alice to encode the secret information. Then the transformed d-dimensional Bell-state two-order sequence is transmitted to the receiver Bob. Combining with some classical information, the transmission of secret message is achieved by using the results of respective POVM measurement and the entanglement characteristics of Bell state particles. By using entropy theory and probability theory, the protocol security is analyzed. Results show that the proposed scheme is secure, and it has a higher transmission efficiency and a rise of 11% in the eavesdropping detection rate than that of the scheme proposed by Chang Yan et al.