An efficient and secure two-way asynchronous quantum secure direct communication protocol by using entangled states is proposed in this paper. Decoy photons are utilized to check eavesdropping; the securities of the protocol are equal to BB84 protocol. After ensuring the security of the quantum channel, both parties encode the secret message by using CNOT operation and local unitary operation separately. The two-way asynchronous direct transition of secret message can be realized by using Bell measurement and von Neumann measurement, combined with classical communication. Different from the present quantum secure direct communication protocols, the two parties encode secret message through different operations which is equivalent to sharing two asymmetric quantum channels, and the protocol is secure for a noise quantum protocol. The protocol is efficient in that all entangled states are used to transmit secret message.