We present a quantum secure direct communication protocol where the channels are not the maximally entangled states. The communication parties utilize decoy photons to check eavesdropping. After ensuring the security of the quantum channel, the sender encodes the secret message and transmits it to the receiver by using controlled-NOT operation and von Neumann measurement. The protocol is efficient in that all pure entangled states are used to transmit the secret message. As for the experimental feasibility, our protocol can be realized with today's technologies. The protocol is also verified to be secure for a noise quantum channel.