At present, functional organic molecule is a study focus in exploitation of new type photoelectron material and photosensitizer of photodynamic therapy (PDT), therefore it is necessary to study a new-type photosensitizer hypocrellin A (HA) which belongs to excited state intramolecule proton transfer (ESIPT) molecule, that is, HA′s basic properties of spectroscopy and electronic excited state properties. As a result, the stimulative phenomenon of HA is found, the rage of laser emission is 620～800 nm, providing a new proof for ESIPT under intense excitation. The fast process of HA′s excited state is investigated by transient grating technology, it is believed to be a result from the decay of transitional state (TS*) produced by skeleton rearrangement. Its lifespan is 10.5 ps.