To explore the influencing factors of explosion accidents caused by gasoline leakage in a confined space, the effects of ignition delay time, ignition energy, initial pressure, initial temperature and mass concentration on gasoline vapor explosion pressure and flame propagation velocity were investigated using a 20 L spherical explosion vessel. The dynamic explosion temperature distribution of gasoline vapor was mapped by the colorimetric thermometry, and the results demonstrated that the optimal ignition delay time, ignition energy and mass concentration of gasoline vapor in the confined space were 100 ms, 100 J and 160 g/m3, respectively. When the initial pressure was 0.11 MPa, the deflagration pressure of gasoline vapor explosion reached the maximum of 1.08 MPa. The influence of the increasing initial temperature on the maximum explosion pressure rise rate of gasoline was greater than that on the explosion pressure and combustion duration. When the mass concentration of gasoline vapor was 160 g/m3, the flame propagation velocity and average temperature both obtained their maximum values of 1.23 m/s and 2271 K, respectively. The research results were conductive to reveal the mechanism of explosion accidents caused by gasoline leakage in a confined space, and may provide theoretical guidance for safe storage and transportation of gasoline.