Abstract: To address the problem of contamination and jamming in hydraulic servo spool valve, a two-dimensional axisymmetric model with groove and clearance was established. The Euler-Euler multiphase flow model of Fluent was used to simulate and analyze the movement and accommodation characteristics of the contamination particles. The study shows that the particles in the groove are vertically stratified, and they fluctuate in multiple peaks along the flow direction of the sudden expansion-sudden contraction gap. As the groove width increases and the groove depth decreases, particles tend to accumulate in the outlet region of the groove, which is likely to induce contamination jamming of the spool. Among different groove shapes, the semicircular groove shows the most pronounced particle enrichment at the groove bottom. The results provide an important theoretical basis for the optimal design of highly reliable hydraulic servo valves.