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2D servo valve combines the pilotstage and powerstage together based on the spiral servo principle. The throttles of the pilotstage have a decisive influence on the characteristics of the 2D servo valve. The dynamic characteristics of bow and rectangular pilotstage 2D servo valves were analyzed, especially under the influence of structural parameters. Firstly, the structure and working principle of the 2D servo valve were introduced, and then the mathematical models of the bow pilotstage 2D servo valve and the rectangular pilotstage 2D servo valve were established respectively. Secondly, the step characteristics of the bow and rectangular pilotstage 2D servo valves under different structural parameters (inclined groove β, pilot stage zero opening h0, system pressure ps) were simulated by numerical method. Finally, a test rig was set up to verify the step characteristics of the bow and rectangular pilotstage 2D servo valves. As a result, the experimental curves of step characteristics of the bow and rectangular pilotstage 2D servo valves were obtained. Under the same structural parameters (inclined groove β was 82°, pilot zero opening h0 was 002mm) and system pressure ps (20MPa), the step response time of the 2D servo valve was shortened from 34ms (bow pilotstage 2D servo valve) to 14ms by adopting the rectangular pilotstage structure. Moreover, the rectangular pilotstage structure was applied to a 2D electrohydraulic servo valve which a torque motor was employed as electro〖JP3〗mechanical converter to drive the rotary motion of the spool. When the displacement of the spool was 03mm,〖JP〗 the step response time of whole system was 10ms, which showed that rectangular pilotstage electricalhydraulic 2D servo valves driven by the torque motor can demonstrate a high speed of response.