Abstract: According to the acoustic simulation mechanism of mobile acoustic decoy, this paper establishes a simulation model of the radiated noise property of mobile acoustic decoy and a simulation model of sound reflection. It analyzes three differences of acoustic characteristics between mobile acoustic decoy and submarine: 1) directivity difference, i.e. the directivity of radiated noise of submarine borders on isotropy while the directivity of the simulated radiated noise of decoy lies on the emissive directivity of transmitting transducer; 2) target strength difference, i.e. the target strength of submarine changes following the incident angle of sound wave, while the simulated target strength of decoy lies on the emissive directivity of transmitting transducer; 3) dimension difference, i.e. the dimensional characteristic of decoy differs from that of submarine. It is suggested to make use of the directivity difference between simulated radiated noise of decoy and radiated noise of submarine and the difference between dimensional characteristics of decoy and submarine to counter against mobile acoustic decoy.