An underwater pipeline inspection device launcher assembly used by an unmanned vessel, comprising: a sled-shaped pipeline base (14) with a plurality of guiding shafts (16) extending upwards and an inclined support (24), the inclined support (24) is used for securing an upward sleeve or flange (26) connecting to one end of a pipeline (28). The pipeline inspection device launcher (12) used by the unmanned vessel can be lowered to the pipeline foundation (14). The pipeline inspection device launcher (12) comprises an opening alignment guide (18) consisting of a plurality of sleeving tubes (22) forming a downward connection to a funnel-shaped portion of a guide shaft (16). The underwater pipeline inspection device launcher (12) assembly (10) is used to perform inspection and testing of an unmanned vessel. The invention can address the technical issues of limited range and low accuracy of inspection and testing.