Abstract: The D(d, γ)⁴He fusion reaction at low energy was studied in this paper. Due to the small yields, the high energy and the strong background of γ-ray, a big NaI-plastic scintillator anti-Compton spectrometer was employed to increase the detect efficiency and reduce the impact of the cosmic rays, and the method of the time-of-flight (TOF) was used to discriminate neutron and gamma to reduce the background of neutron and cosmic rays. The thick and thin deuterium-loaded titanium target experiments were performed at E_d=300 keV. The background was subtracted by our fitting method. The cross section is 2.47×10^-37m² for the thick target and 4.36×10^-37m² for the thin target.