The invention discloses a patch type piezoelectric driving double-propeller underwater vector propulsion system and method, the system comprises a piezoelectric driving unit, two propellers and two rudders, and the piezoelectric driving unit comprises a metal matrix and eight piezoelectric ceramic parts; the propeller comprises a fixed shaft, a rotating drum, n blades, a pre-tightening bolt, a spring and n actuating rods; the rudder comprises a direction plate, two clamping plates, four fixing bolts and two tension springs. The forward and reverse propeller rotor combination adopted by the invention rotates simultaneously to balance deflection torque. the two rudders generate precompression with the piezoelectric driving unit through the tension spring. In the working process, different signals are applied to the eight piezoelectric ceramic parts, friction is generated, the piezoelectric ceramic parts advance, retreat or steer, and vector propulsion is achieved. The structure is simple, no sealing device and no complex transmission structure exist, the piezoelectric driving technology is adopted for direct driving, and miniaturization and light weight are easy to achieve.