The invention provides a hydrocyclone which efficiently separates a high-concentration liquid-solid mixture and is used for realizing efficient separation of the oil and solid particles of the petrochemical industry. In the invention, efficient liquid-solid separation is realized by use of the density difference between the liquid and solid phases as well as the different centrifugal forces experienced by the liquid and solid phases. The high-concentration liquid-solid hydrocyclone comprises a cylinder (4), an overflow pipe (6), a square feed port (5) and a cone (3), wherein the overflow pipe (6) is mounted at the top of the cylinder (4); the square feed port (5) is located at the upper part of the cylinder (4) and horizontally connected with the cylinder (4) along the tangential direction; the cone (3) is arranged at the lower part of the cylinder (4); and a flow stabilizing rod (2) is required for a relatively small cone discharge port (1). By reasonably matching the structural sizes of the parts, the liquid-solid hydrocyclone provided by the invention realizes efficient separation of liquid and high-concentration particles; at normal temperature and pressure, the separation efficiency of the high-concentration liquid-solid hydrocyclone on the mixture of water and FCC (Fluid Catalytic Cracking) catalyst, with volume concentration of 15%, is 83-93%; and the liquid-solid hydrocyclone provided by the invention can be widely applied to the separation of a high-concentration liquid-solid system in the petrochemical industry.