The improvement in the rotation rate of thermally-induced isomerization is an essential feature for improve the operational efficiency of light-driven molecular motor. In this paper, we investigate the Z-to-E photoinduced nonadiabatic molecular motor possessing lower thermal isomerization barrier by up to 25 kJ mol -1 developed by Wang et al. It further improved the thermal isomerization performance of overcrowded alkenes by reducing the sizes of the rotator and stator hales of some specific larger system and fastest available molecular motor. In this paper, we systematically investigate the photo-induced isomerization mechanism of a synthetic molecular motor based on overcrowded alkene molecular compound using trajectory surface hopping dynamics method at a semiempirical OM2/MRCI. Research indicates that the calculated quantum yield of the E-to-Z photoisomerization of this molecular rotary motor is about 13.09%, and the average lifetime of the excited state is 1230 fs. Additionally, the time-dependent fluorescence radiation spectrum is calculated and the fluorescence emission quenching accom­panied by red shift of wavelength is observed, and the presence of a “dark state” during the decay process is thus proposed.