Abstract: The flow resistance of the integrated valve is one of the key parameters for the design of the control rod hydraulic drive system (CRHDS). Experimental research on the improved new integrated valve was performed, and the key data such as pressure difference, volume flow, resistance coefficient and flow coefficient of each flow channel were obtained. With the computational fluid dynamics software CFX, numerical simulation was executed to analyze the effect of Re on the flow resistance. On the basis of experimental and numerical results, fitting empirical formulas of resistance coefficient were obtained, which provide experimental and theoretical foundations for CRHDS’s optimized design and theoretical analysis.