A height-adjustable profile steel fixing device comprises a pair of oppositely-arranged chucks, adjusting rods respectively installed at two ends of each chuck and two bottom fixing rib plates respectively installed at the bottoms of the adjusting rods, wherein the two bottom fixing rib plates are respectively fixed to bottom supporting rods, and a frustum-shaped frame structure is formed. The height-adjustable profile steel fixing device can be adjusted in height according to the swing height during blocking profile steel prefabrication and is more convenient to use, and the problem that an existing profile steel fixing inclined strut cannot be adjusted in height is solved. In addition, the influence produced by cutting, grinding and other work delay caused by inclined strut welding is eliminated, construction difficulty is reduced, and the bearing capacity and production efficiency of a cushion pier are improved.