The drilling practices of oil and gas wells have proved that reducing the Bottom-Hole Differential Pressure (BHDP) is able to significantly improve the Rate of Penetration (ROP), reducing the drilling cost. The structure features, depressurization capacities, and the current researches and developments of Equivalent Circulation Density (ECD) reduction tool, vortex joint, and vortex bit are summarized based on the analysis of the depressurization theory of the vortex tools. The numerical simulation analysis is carried out to study the bottom hole flow field of the vortex Polycrystalline Diamond Compact (PDC) bit using the CFD software, the results show that the critical factor affecting the vortex bit depressurization capacity is the reliable sealing of the annulus between the vortex bit and the borehole walls. 150°-180° is recommended for the angle of the reverse nozzle, and more than 32% of the total circulation drilling fluid is also recommended as the upflow, providing the theoretical guide for the development of the vortex bit.