The invention discloses a comprehensive damping method mixed explosion of a hard rock tunnel closely attaching to an existing underground building. The method is characterized in that below the base plate of the existing structure of the existing building, an explosion working face is sequentially divided into a metal expansion explosion area, an emulsion explosive underholing area and an emulsion explosive explosion area towards the depth direction. By the method, explosion vibration speed during tunneling, attaching to the existing underground building, in a hard rock stratum can meet the requirements, the existing underground building is not damaged by explosion shock waves, and project progress is guaranteed.