Highly effective integration heat engine

The invention relates to a high efficiency heat engine having combined heat-work conversion process, especially an heat engine integrated with multiple working strokes and multiple working media. The invention has duplex combined type cylinder structure, wherein a first cylinder is a one-time combustion/expansion cylinder, and a second cylinder is a secondary combustion/expansion cylinder. The multiple working strokes driven by the multiple working media are integrated into a whole. These different working media comprise air-fuel burnt products, steam, and compression air under the brake energy regenerating mode of air mixing type. The duplex combined type cylinder structure provides places for the composite expansion of three different working media, and can capture the energy lost in the working media emission and braking process. The structure causes the heat engine of the invention can work in six work periods composed of twelve strokes. In the six work periods, four periods comprises four different worki