Abstract: The theory of field-matching to build scattering matrix method was established to analyse optimization calculation for the multiple-disk output window. Through a lot of numerical calculation program design, the structure parameters of Q-band gyro-TWT double disk output window were given. Then by high frequency software HFSS simulation verification, the wide-band output windows of Q-band with band width about 4 GHz when S11 parameter is less than -20 dB were attained. Finally, on the basis of the further research, using a new method of collaborative simulation, thermal analysis of software ANSYS and HFSS was carried out on the double-disk output window to research the thermal property and power capacity of the new type output window with wind cooling. The research shows that the temperature difference of the new type output window compared with traditional output windows dropped significantly and the power capacity increased by 21.8 kW to 90 kW saturation power capacity.