Three critical technologies of simulation analysis on thermal-loads of radome in flight are selected to study in this paper. Section 2 analyzes the first critical technology, which is modeling of the radome and the antenna. And the computational fluid dynamics software FLUENT is used to analyse the radome, so as to calculate the temperature distribution of its outer surface. Section 3 analyzes the second critical technology, which is to establish the multi-cavity thermal radiation model of the radome so that to get the temperature distribution of the inner surface. A kind of interpolation method, which is the third critical technology, is used to transfer the temperature of flow field and the space heat radiation to the corresponding thermal-stress analysis model of radome.