Abstract: Based on the safety spark test apparatus, the low voltage Inductor Disconnected Discharged (IDD) characteristics were studied through explosion experiment. The low voltage IDD characteristics were analyzed. The experimental research state, mathematical model and discharge time of the arc discharge were expounded in detail; the micro mechanism models of the arc discharge were discussed. Thus, the clear ideas were got in order to further study the low voltage IDD characteristics; the assessment theory of the intrinsic safety was introduced from different aspects. Finally, some problems to be solved were explored in the study of the arc model.