Abstract: As an important component of the amplifier, the flash lamp pumping efficiency directly affects the amplifier efficiency. Compared with the traditional flash lamp, the new structure flash lamp with a vacuum bubble inside (annular flash lamp) is proved having the advantage of higher radiation efficiency. This paper studies the influences of different pressures and structures on the annular flash lamps' discharge, radiation and explosion characteristics. Results indicate that increasing the pressure and internal diameter of annular flash lamp can improve the radiation efficiency. The fluorescence from the neodymium glass can be improved by 22.3% of peak value and 15.7% of integral value. However, increasing the pressure and internal diameter will deduce the thermal load limit. It is experimentally demonstrated that the annular flash lamp with 26 664 Pa and internal diameter 30 mm has the highest radiation efficiency and can pass lifetime test.