The agitator can improve the effectiveness of bit weight transfer and reduce the friction between drilling tool and borehole through the longitudinal vibration produced by the hydraulic action of drilling fluid, especially in the process of directional drilling to improve the bit weight transfer and reduce torsional vibration. It is a downhole tool used to solve downhole depressurization and improve weight on bit transfer. Smooth weight on bit transfer improves the ability to adjust the bit toolface to reach further target zones. It does not require too much work to adjust the tool face during drilling, keeping the tool face stable and increasing ROP. Particularly suited for horizontal, extended-reach Wells, it can be used in conjunction with MWD, screw, and any bit.