The efficient generation of amplified spontaneous emission (ASE) in 2- (2'- hydroxyphenyl) benzoxazole (HBO) in cyclohexane solution based on excited state intramolecular proton transfer (ESIPT) is reported. The gain coefficient (α) for ASE(510 nm) of HBO is measured as about 1. 2 cm-1, nearly equal to that of rhodamine-6G under similar conditions in our apparatus. Based on ESIPT processes of HBO, a kinetic model for ASE is developed to simulate numerically the gain spectra and ASE spectra. The agreement between the computed results and experiment is very satisfactory with a τs0s0' value of 260 ns. This fact sugguests that the lifetime of ground state keto tautomer (K) is more likely to be 260 ns rather than subnanosecond.