The invention discloses a long-stroke floating head support. The long-stroke floating head support comprises a floating cushion block, a lifting rod and a base, wherein a support plane is formed at the upper end of the floating cushion block; a concave spherical surface packing is arranged at the lower end of the floating cushion block; a convex spherical surface head is arranged at the upper end of the lifting rod; the concave spherical surface packing is positioned on the convex spherical surface head in a floating manner; the lifting rod can lift and drop to be positioned on the base. The convex spherical surface head and the concave spherical surface packing are matched, so that automatic floating type full-area contact supporting of the floating cushion block and a workpiece is realized in a supporting process, the support is stable, support points are stressed evenly, the contact area of the workpiece cannot be pressed, the workpiece can be in a working state of minimum deformation, and the assembling precision of the workpiece is guaranteed; the lifting rod has a wide lifting range and is convenient to use and adjust, time-saving and labor-saving, and the long-stroke floating head support can be applicable to support and tight padding of various large workpieces.