Abstract: Based on the aerospace application requirements and the characteristics of the pulse-width modulators, this paper investigates the content and the methods of the assessment tests for the pulse-width modulator for aerospace applications. Some key indexes or characteristics are evaluated, such as the temperature drift of the typical oscillation frequency before and after the life test, the temperature drift and the long-term stability of the reference voltage, and the swing of the oscillation frequency at different external oscillation resistances and capacitances. These are validated by the evaluation tests. The results can provide comprehensive data support and guidance for the aerospace applications of the pulse-width modulation.