Abstract: A finite element model of the high-speed aerocraft infrared optical dome in the aerodynamic heating environment was established to analyze the domes physical and optical properties. The temperature filed, stress field, strain field and displacement field of the dome in the aerodynamic heating environment were computed numerically. The calculated results show that the temperature distribution of the dome in aerodynamic heating environment is non-uniform and thus the dome is deformable due to its thermal stress. Based on the theories of thermo-optical effect and elasticoptical effect, the refractive index field of the dome was numerically computed with the result of the finite element analysis. Taking the refractive index of the central point in the domes outer surface as an example, the refractive index variation caused by thermo-optical effect is 0.011 while the xdirection refractive index variation caused by elastic-optical effect is 0.000107. That is, the refractive index variation caused by elastic-optical effect is only 0.97% in the amount of the refractive index variation caused the thermo-optical effect during the domes working time. Therefore, thermo-optical effect has greater influence on the refractive index variation of the dome than elastic-optical effect.