Abstract: Improving the sound insulation performance of prefabricated light-gauge steel framing composite external wall will effectively promote the development of green buildings and improve the building quality. In this paper, the sound insulation performances of six kinds of prefabricated light-gauge steel framing composite exterior walls with different structures are measured in the sound insulation laboratory. The effects of fiber cement board and gypsum board as coating panels, sound absorption materials with different thicknesses, vibration reduction treatment of component connection, and external insulation decorative boards with different thicknesses on the sound insulation performance are compared and analyzed. The results show that fiber cement board is more favorable for sound insulation performance than gypsum board. The greater the thickness of the light-gauge steel framing cavity filled with sound absorption material, the better the sound insulation performance of the wall. The vibration reduction treatment at the connection of wall components does not significantly improve the sound insulation performance. The sound insulation performance of prefabricated light-gauge steel framing composite exterior walls cannot be improved by adding external thermal insulation decorative board and increasing the thickness of external thermal insulation decorative board. The research result in this paper can provide data support and an important reference for the design and production of prefabricated light-gauge steel framing composite external wall.