The invention provides a hole blocking device for preventing an open-air blast hole from being blocked. The hole blocking device at least comprises a lifting handle and a plug body; the lifting handle and the plug body are all plastic; the lifting handle and the plug are formed in at a time through injection molding and are an entirety; the plug body is a hollow cone, and the bottom diameter of the cone is 3-4 cm greater than the diameter of the blast hole; a rubber strip is arranged on the circular conical surface of the plug body along the generatrix, and the rubber strip extends out of the circular conical surface; and the lifting handle is a ring, the ring is fixed to the bottom center of the cone, and the surface of the ring is covered with a reflective coating. The hole blocking device provided by the invention is simple is structure, convenient to use and low in price, is integrally formed through injection molding at a time, is high in strength, is light in mass and can be utilized repeatedly; the problems that the blast holes are blocked by broken stones or other sundries because of rain, wind, machine movement and walking of workers on spot are avoided; and the lower portion of the hole blocking device is the hollow cone to reduce the integral weight, the upper portion of the hole blocking device is the ring for being fetched and used conveniently, and the ring is covered with the reflective coating for quickly positioning the blast holes.