The invention discloses a resin tank for a digital light processing (DLP) photocuring 3D printer. A periphery mounting face is formed at the bottom of a box frame, a soft cushion plate is arranged under the periphery mounting face and fixedly attached to the periphery mounting face, and a fluorinated ethylene propylene copolymer thin film or a teflon thin film is clamped between the periphery mounting face and the cushion plate. The box frame can be lifted relative to a bottom plate through external force and can be reset in time after the external force is gone, an opening is formed in the bottom plate and located in the box frame, and a transparent sealing plate covers the opening and is fixed through a cambered pressing frame. When the box frame is kept in a downward-pressing state through the acting force of spiral springs, part of the cambered pressing frame extends into the box frame, and the fluorinated ethylene propylene copolymer thin film or the teflon thin film is tensioned. The technical purpose that the bottom of the resin tank can be conveniently stripped from cured resin in the working process of the DLP photocuring 3D printer is achieved, and the printing effect is improved.