The invention discloses a sound baffle assembly used for an underwater detection device. The sound baffle assembly comprises the underwater detecting device, a sound insulation baffle and a sound absorbing baffle, wherein the sound insulation baffle is arranged horizontally behind the underwater detecting device, the sound absorbing baffle is longitudinally arranged, and the sound absorbing baffleis positioned between the sound insulation baffle and the underwater detecting device. For the sound insulation baffle, the functions and structures including damping, sound insulation, sound absorbing and the like are integrated in design, the sound insulation volume of the sound insulation baffle can achieve 15dB, the sound absorbing coefficient can achieve 0.9 or above, two sides of the soundabsorbing baffle adopt sound absorbing wedges as second sound absorbing layers, the sound insulation structure is arranged in the center and plays the supporting role, the sound absorbing coefficientof the sound absorbing baffle can achieve 0.9 or above, the insertion loss for sound signals is 8dB, the sound insulation baffle and the sound absorbing baffle are used in a combined manner behind theunderwater detecting device, under the condition of guaranteeing the 150-degree visual angle of the underwater detection device, the noise reduction can achieve 3-8 dB, and therefore, the signal-to-noise ratio and gain of the underwater detection device are improved.