The invention provides a combined mechanical pressure release anti-backfire device, comprising an inlet pipe, a housing, an elasticity film, a fire stopping pipe, a connecting piece, a spacer and a mechanical pressure release valve, wherein, the fire stopping pipe is fixedly connected with the connecting piece, and the connecting piece and the fire stopping pipe are installed on the step hole endsurface in the housing in an abutting mode by the spacer sheet of the inlet pipe; the elasticity film is sheathed on gas discharging through holes of each line of the inlet pipe which is fixedly connected in the housing by threads; the mechanical pressure release valve is installed on the upper end of the vertical through hole on the housing by threads. The invention can use the fire stopping pipe to cut off or extinguish the fire entering the inner cavity when the backfire phenomenon appears; at the same time, pressure wave passes through the inner cavity of the fire stopping pipe before deflagration fire to quickly push inwards, inner cavity pressure raises to cause the elasticity film to perform functions so as to cut off a gas loop; simultaneously, protective pressure release is carried out by the mechanical pressure release valve when the inner cavity pressure raises to a set safe value to release high pressure produced by backfire, so that the invention can effectively ensure the safety of the device and prevent the backfire phenomenon from damaging devices.