To solve the problem of valve noise, a multi-hole sleeve valve with secondary pressure-reducing function is presented in this paper. During the flow design of the valve, the flow resistance coefficient of the valve served as an important parameter. Because of two pressure-reducing components assembled to a multi-hole sleeve valve, the flow resistance coefficient of the valve changed. Thus, correction of the flow resistance coefficient had to be affected. In this paper, the relationship between the flow rate and flow resistance coefficient of the valve was first mapped and established. Then, the flow rate of the sleeve was obtained using SolidWorks simulation software. Locally refined finite element mesh technology was applied to the simulation to improve simulation accuracy. A parallel flow test platform for the regulating valve was established, and the flow rate of the multi-hole sleeve valve was detected at different openings, thus, verifying the reliability of the numerical simulation results. Finally, the simulation flow rate of the valve at different openings was substituted into the mapping relationship formula, in this way, the flow resistance coefficient of the sleeve valve was obtained. By using the modified flow resistance coefficient, the flow rate characteristics of the multi-hole, secondary pressure-reducing sleeve valve were efficiently and accurately established.