Abstract: The flow conductivity of baffle valves is generally solved using approximate equivalent methods or steady-state numerical simulation methods, and the accuracy and applicability of the solution results need to be improved. This paper presents a novel approach, based on the Reynolds-Averaged Navier-Stokes (RANS) and Navier-Stokes (NS) equations, to model the flow conductance of baffle valves. A dynamic model encompassing a vacuum chamber, regular pipe, and baffle valve was developed to simulate the low vacuum pumping process of continuous flow gas with Fluent's transient solver. By monitoring the pressure and flow rate of the inlet and outlet of the baffle valve, the flow conductance values of the baffle valve at different pressures are determined, and the flow conductance calculation formula of the baffle valve is obtained by fitting with the least squares method. The validation experiments of the simulation method show that the simulated flow conductivity values are in good agreement with the theoretical values, which verifies the accuracy and applicability of the method. The baffle valve flow conductance formula is applied in the calculation of the pumping prediction curve, and the comparison of the pumping prediction curve and the pumping experimental curve revealed that the relative error between the predicted and actual values of the pumping end time was 4.76%, it is shown that the baffle valve flow conductance formula obtained in this paper is practical and reliable. This study can provide methodological references for the calculation of flow conductivity of special-shaped pipeline components in low vacuum pumping processes.