Aiming at the common cavitation problem of the cage-typed control valve in the coal liquefaction industry, based on the RANS equation, the mixture multiphase flow model and the Zwart cavitation model, a numerical simulation study of the cavitation flow inside the valve was carried out, and the main reason of the cage's failure was determined. Based on the pressure drop analysis and prediction of the cavitation position, a structural improvement scheme of the control valve's cage was proposed and verified. The results showed that the cavitation vapor in the control valve was concentrated in the inner orifice of the cage, which was the main reason for the obvious failure defects in the inner wall of the inner orifice and the cage. Based on the comparisions between pressure drop and cavitation vapor distributions on the horizontal cross section of the valve cage, the two reasons for the serious cavitation in the inner orifice of the cage were concluded. Firstly, the number of depressurization stages was not enough, which led to excessive pressure drop in the second stage, resulting in a local low pressure area, and cavitation occurs violently. Secondly, the depth of the inner orifice was too large, resulting in fully developed cavitation in the inner layer orifice of the cage. Thus, the structure improvement scheme was proposed to control the depressurization intensity and the occurrence area for cavitation development in the cage. By adjusting the straight orifice in the inner layer of the valve cage to stepped orifice, the adjustment from two-stage to three-stage depressurization was realized, which solved the problem of local low pressure area caused by excessive pressure drop, and effectively reduced the strength of cavitation initiation and the distribution range of cavitation. This work has a certain reference value for the design and research of the cage-typed control valve in the coal liquefaction industry.