Abstract: During the process of cryogenic wind tunnel operation, low temperature and a wide range of temperature variation lead to strong thermal stress and deformation of structure circuit, which may decreases the aerodynamic performance and safety of cryogenic wind tunnel. In order to control the thermal deformation and decrease thermal structure stress, several technological approaches have been applied in the 0.3 m cryogenic wind tunnel structure design, including selecting most reasonable cryogenic materials, active heat transfer in plenum chamber, stress and deformation releasing design and thermal stress calculation by using Finite Element Method (FEM). Calculation shows the ultimate thermal stress appeared on plenum chamber pressure shell, extending to 110 MPa after the 7200 s cooling down process of 0.3 m cryogenic wind tunnel, with a 110 K and 250 K strucure temperature on corner vanes and shell flange respectively. The predicted structure safety factor is greater than 1.8. The ultimate thermal deformation is appeared on the fourth corner shell when the circuit temperature cooling down to 90 K, contracting to 29 mm in aero axes direction and 12 mm in crossleg axes direction, respectively. The subsequent wind tunnel test shows that the simulation results of FEM are consistent with the measure results Calibration indicates that the structural design of 0.3 m cryogenic wind tunnel is reliable.