The utility model discloses a concrete core mold fixing device. The problem of large floating of the core mold is effectively solved; the construction safety is influenced, and the like, including templates, a grid and a core mold are sequentially arranged above the template; a through groove is formed in the middle of the mandrel; a supporting plate penetrates through the through groove; two fixing frames are symmetrically arranged at the left and right ends of the supporting plate; a groove is formed in the middle of each fixing frame; the fixed frame is rotatably connected with a lead screwin the vertical direction; first threads and second threads are arranged on the surface of the lead screw. The first thread and the second thread are both located in the groove and are vertically symmetrical about the center of the groove. The first thread is connected with a first nut, the left end of the first nut is fixedly provided with a first clamping plate located above the supporting plate, the second thread is connected with a second nut, the left end of the second nut is fixedly provided with a second clamping plate located below the supporting plate, and the lower end of the fixingframe is fixedly provided with a base.