The article at hand focuses on the pressure drop at the hydraulic oscillator valve section. The flow path of the valve section is simplified through the hydraulic oscillator working principle and the valve structure. Further, based on the kinematic model of the positive displacement motor (PDM) and the moving valve, the flow area calculation model between valve sections was deduced. Next, using the simplified valve section flow path, said path is divided into four stages, and the analytical model of pressure drop was established by applying the fluid mechanic theory. Aiming to verify the analytical model, the transient finite element model, and the test bench were set up. Finally, three methods were used to calculate the pressure drop within the 1.3-inch and 1.4-inch stationary valves corresponding to the same input parameters. The results have shown that pressure drops obtained by all the methods are in good agreement; the maximum error between the analytical and experimental results was 7.6 %. Additional comparisons were made between the analytical and finite element model (FEM) results at various flow rates. In that case, the maximum error between the two methods was 7.05 %. Thus, the model can be used to further study the hydraulic oscillator mechanisms and provide a useful reference for both the design and optimization.