Laser-induced acoustic signal is a new approach for underwater acoustic source,which has much virtue such as high intensity,short pulse and broad frequency. The acoustic signal characteristic of laser-induced breakdown is studied and its corresponding theory model is systemically analyzed. The experimental measure investigation is formed with the high power laser,water tank and high frequency hydrophone. The characteristic of acoustic signal such as intensity,frequency and transmitting is analyzed. Based on the underwater target detection technology,the experiment of underwater target detection is done through laser-induced acoustic signal. The experimental results show that the laser-induced acoustic signal has a salience role during the small target detection. This makes a stride for investigation of laser-acoustic underwater objects detection.