We propose a novel physical layer scheme to suppress eavesdropping. Different from the existing schemes which are based on secrecy rate enhancement with Gaussian signal, our scheme is executed from the actual signal point of view. In our scheme, we set several structures of constellations for each modulation mode, and then different structures are utilized for different signals' modulations. In this case, on one hand, even though the eavesdropper knows this modulation mode, he#x002F;she is difficult to demodulate each signal. On the other hand, the information related to this constellation selection is safely delivered to the authorized user by a well-designed mechanism. Moreover, an auxiliary artificial interference method is introduced for further confusing the eavesdropper. In a word, our scheme is feasible for physical layer security improvement.