Traditional IGBT turn-on loss evaluation methods are curve fitting of double pulse test data without insight of IGBT turn-on process. This paper proposed an analytical evaluation method of IGBT turn-on loss. In the proposed method, a qualitative IGBT switching waveform and an IGBT switching trajectory in output characteristics are used to analyze IGBT turn-on process. The detailed expressions for turn-on process are derived from an IGBT equivalent circuit model. IGBT switching transients governing equations to model IGBT turn-on loss are simplified. The turn-on loss estimated with the proposed expressions matched reasonably well with the experimental measurements.