Based on theoretical calculation and Monte Carlo simulation, this paper proposes a new method for the diagnosing of 16.7 MeV highenergy pulse gamma, named “scattering absorption method”. The ratio of the sensitivity of highenergy gamma to that of the lowenergy background gamma can reach 106 to 108 by this new method. The sensitivity of 16.7 MeV highenergy gamma ranges from 1021 to 1016 C·cm2. It’s better than the traditional method which is based on the magnetic analyzer and Cherenkov detector on some aspects.