To gain a deeper insight into the sorting of main launching noise sources in underwater weapons, different sub-noise sources and their contribution to the overall radiation noise are analyzed through both analytical and experimental research, focusing on the typical gas-water tank launching device trial model. The acoustic transmission channels of launching noise include hull structure and the seawater-connected domain formed by the pipeline system through which the weapons travels. In the concluded thirteen sub-noise sources, the primary components include 4 structural vibration noises and one impact vibration noise. The former are caused by gas tank seat vibration, tank cylinder wall vibration, torpedo tube wall vibration and piston axial fluctuating force source, all of which radiate noise through two transmission channels. The impact vibration is induced by the piston striking the end wall of the tank and radiates noise mainly through the connected domain. The jet noise radiated by the tube exit flow is comparable to the radiation noise of a quasi-quiet submarine in navigation and makes less contribution to the overall launching noise. The airborne noise of the launching device presents broadband white noise with stepwise elevation, mainly concentrated in high-frequency band, with minimal contribution to the structural vibration noise. The vertical vibration of the gas tank seat and the radial vibration of the tank cylinder wall are significantly affected by the piston’s startup and end crash. The instantaneous vertical impact peak value is one order of magnitude higher than a typical ship diesel engine’s periodic vibration. The radial vibration pulse peak of the tube wall is corresponded to the moment of the piston’s end crash. The ranking of the average vibration levels for the three vibration sources is as follows: gas tank seat vibration, tank cylinder wall vibration, and tube wall vibration.