The invention provides a rotary combustion engine; the main reason preventing the realization of the rotary combustion engine is that the interior of a cylinder is hollow, so that the combustion pressure of fuel can not be transmitted to the physical action base point of a rotor blade. The rotary combustion engine (601) is characterized in that in the cylinder (1), a cut off valve (31) is inserted into the cylinder (1) in a way of being rotatably matched with the rotor blade (20), the fuel and air are injected into a closed layer arranged between the cut off valve (31) and the rotor blade (20) for combustion when the radius direction of the circumference space (8) of the cylinder is cut off, and the rotation is directly supplied to a rotor (10) and a working shaft (3) by virtue of the combustion pressure by taking the cut off valve (31) as the action base point.