Abstract: The operating parameters of neutron tube are important factors for neutron yield. In order to control the neutron yield of D-D neutron tube more accurately, the relationship between the working parameters and the yield of neutron tube was tested. At the same time, in order to improve the current quality and life of neutron tube, the secondary electron suppression of neutron tube was tested. The influence of thermionic current, anode high voltage and target high voltage on neutron yield and the relationship between secondary electron suppression resistance and target current of D-D neutron tube are studied by controlling parameter variables. The results show that the neutron yield increases with the increase of thermionic current. When the target voltage is -80 kV and the anode voltage is 2.6 kV, the optimal control range of the thermionic current is 290-305 mA. There is a nonlinear relationship between anode high voltage and neutron yield, and the optimal working voltage needs to be higher than 2.6 kV. The neutron yield increases with the increase of target high voltage, and the higher the high voltage is, the faster the neutron yield increases. The optimal working range of target negative high voltage is -120--100 kV. The secondary electron suppression resistance of D-D neutron tube is 8.7 MΩ or the suppression voltage is 403 V, and the secondary electron can be completely suppressed. The relationship between working parameters and neutron yield can provide a reference for the self-regulation of yield stability of neutron tube in the future. The secondary electron suppression experiment provides a basis for controlling the generation of secondary electron current.