Abstract: To research the influence of the T-shaped branch structure during the explosions of gasoline-air mixture in pipelines, the explosion wave overpressure of gasoline-air mixture explosion in the T-shaped branch pipeline and the straight pipeline at different initial volune fractions were measured through contrast experiments, and the flame propagation rules were researched in an organic glass pipeline by visualized study. The results show that the T-shaped branch pipe can strengthen the explosions of gasoline-air mixture in pipelines, which is the most obvious within the volume fraction range of oilgas from 1.2% to 1.6%. The effect of the T-shaped branch pipe to strengthen the explosion of gasoline-air mixture comes from three aspects: the sudden enlargement of the pipeline cross section, the reinforcement of the disturbance and the obstacles, and the influence of the reflection and diffraction of the waves. When the flame propagates to the T-shaped branch pipeline, the flame front creases distorted, the flame surface area and combustion rate increase significantly, which enhances the heat and the transport rate of active material and improves the strength of the explosion waves. Near the T-shaped branch pipe, the pressure of gasoline-air mixture explosion increased suddenly, both because of the temperature effect caused by the pressure wave reflection and diffraction, and the turbulence intensity increased by explosion waves.