Abstract: Objectives This study investigates the motion characteristics of deep-sea vehicles during high-depth vertical transit under vectored propulsion. Methods Motion equations were established to obtain preliminary solutions for helical diving parameters. Subsequently, steady-state turning diameter, heeling angle, and multi-parameter-influenced powered helical diving tests were conducted on a lake using a vectored-propulsion deep-sea vehicle prototype to analyze diving motion characteristics. Finally, a 3650-meter powered diving test was performed in real-world conditions at 3700-meter depths in the South China Sea. Results Lake trials demonstrated that the vectored-propulsion deep-sea vehicle achieved a stable turning diameter of just 4 times its total length with ≤2.5° heeling angle. Under selected control parameters, it maintained a 0.6 m/s average diving speed with 0.42° pitch angle standard deviation. Post-dive analysis after the 3650-m dive revealed a 442-m horizontal drift. Conclusions The vectored propulsion approach demonstrates technical feasibility for powered diving in deep-sea vehicles, exhibiting stable and controllable motion characteristics throughout operations. These findings provide valuable references for further research in this field.