Fastening device, elevation control support and high-low straddle formwork support

The utility model belongs to the technical field of building construction, and discloses a fastening device, an elevation control support and a high-low span formwork support. The fastening device isused for installing the hydropower embedded part, the template support and/or the elevation control support on the template, the fastening device comprises a first connecting part and a second connecting part which are connected with each other, the first connecting part is connected with the connecting ends of the hydropower embedded part, the template support and/or the elevation control support, and the second connecting part is connected with the second connecting part. The second connecting part is fixedly connected with the template; the acting force between the first connecting part andthe connecting end is smaller than that between the second connecting part and the template; and at least one part of the structure in the first connecting part can be separated from the connecting end and is fastened and con