On the SF6 discharge decomposition experimental platform, the SF6 decomposition product is explored under small spark discharge in needle-plate defect model. The discharge test is made for 96 h under 40 kV, and Fourier transform infrared spectroscopy was used to detect the decomposition product. It is found that the components are varied with discharge time, the gases of SO2, SO2F2 and SOF2 are obviously detected in the gap spark discharge and the absorption peaks of the gases are obtained after 24 h.