The invention relates to a hollow square tube character pressing device. The hollow square tube character pressing device is characterized by comprises a lower mold plate, a wedge block support, an upper mold assembly and a demolding tapered wedge which are used in cooperation; the lower mold plate is provided with a side positioning stopping part and an end positioning stopping part; the wedge block support comprises an upper wedge block and a lower wedge block, self-locking slopes which are matched with each other are machined at the lower portion of the upper wedge block and the upper portion of the lower wedge block, and the upper wedge block is provided with a square hole where the demolding tapered wedge is inserted; and the upper mold assembly comprises a fixing plate, an initial block and a pressing plate, the fixing plate is arranged at the bottom of the pressing plate, and the initial block is installed in a character block square hole in the middle of the bottom face of the fixing plate. The hollow square tube character pressing device is fastened into a hollow square tube in a wedged manner, looseness caused by slippage of the upper wedge block during pressing printing can be avoided, the beneficial effects of being large in support body strength, simple in operation and convenient are achieved, deep type permanent marker pressing can be achieved, and pressing printing deformation can be avoided.