The invention discloses a method for establishing an internal leakage model of a vane type continuous rotary electro-hydraulic servomotor. The invention is intended to fill a blank field of an internal leakage mathematic model, which is based on numerical simulation and theoretical calculation in a micro clearance and in different working conditions, of the vane type continuous rotary electro-hydraulic servomotor, so as to establish an internal leakage model of a motor. The method for establishing the internal leakage model of the vane type continuous rotary electro-hydraulic servomotor comprises the following steps: step A, establishing internal leakage formulas of four positions of the motor; step B, analyzing four working conditions of the motor; step C, establishing a fluid model formed by enclosing a stator, a rotor, a vane and an oil distribution disc; step D, carrying out grid division on the four fluid models by using CFD (Computational Fluid Dynamics) software, importing files in CFX (Computational Fluid X) to simulate calculation in a stable state, and establishing solid models of the stator, the rotor, the vane and the oil distribution disc; step E, establishing a workflow chart in a WORKBENCH, and carrying out fluid-solid coupling analysis on the motor; step F, obtaining aberration nephograms of all components through the post processing by the WORKBENCH, substituting aberration nephograms of all the components into the corresponding formulas in step A, so that a leakage amount caused by an initial clearance and solid-fluid coupling deformation can be obtained.