Abstract: STUDY OF TAKING OUT THERMAL NEUTRON BY USING DD SEALED TUBE NEUTRON GENERATORZhong Haiming(Department of Physics, Northeast Normal University, Changchun 130024)Li Haiying(Deparment of Physics, University of Science and Technology of Changchun, 130023)Abstract A smallsize installation using DD sealed tube neutron generator to take out thermal neutron is introduced. The optimum model to draw out thermal neutron from polyethylene moderator is determined by experimental method, and the good thermal neutron source to practical application of thermal neutron is provided.Key words neutron generator moderator distribution of fluence rate thermal neutron