Abstract: To measure the amount of pulse fission neutrons, we carried out the theoretical research of a new method. This paper introduces its principle of measuring pulse fission neutrons, states a new detection system for measuring the neutrons with a radiation attenuator and carried 6Li plastic scintillation detector, and method of neutron sensitivity compensation, that can adapt the measurement need. And this paper gives the simulating calculation results of the system parameters. In the conclusion, it analyses the merits and the potential application of this method.