Amplified spontaneous emission lifetime (ASEL) distribution characteristics of the new BaAlBO3F2 (BABF) crystal have been calculated via the equations of emitted light intensity and amplified signal intensity gain. The ASEL distribution was calculated and discussed for three types of injection into the BABF crystal based on an optical parametric amplifier. We found ASEL was first distributed mainly in an ellipsoid and then in a torus with the increase of the pump phase matching angle when a monochromatic signal is injected. For the polychromatic signal pulse injection, ASEL is changed from a scattered distribution to a concentrated distribution. For the broadband pump, the ASEL distribution range is greatly expanded because of the increasing phase matching range.