The invention provides a broadband low-intermodulation omni-directional ceiling antenna which includes a radome, a radiator, a bottom plate, a connecting screw, a mounting bolt, and a cable. The antenna is characterized in that a mounting nut plate and a plunger are arranged; the radiator is a shell integrally made of a metal material, square slots are uniformly distributed on the shell, and the same number of grounding pieces as the slots are distributed around the shell; the cable passes through the plunger, the connecting screw and the bottom plate, and after the plunger is in threaded connection with the lower end of the connecting screw, the cable is fixed through partial structure deformation of the plunger; and the mounting nut plate is mounted outside the connecting screw, and is open. Compared with the prior art, provided with the integrally formed radiator, the plunger with a fastening function and the open mounting nut plate, the broadband low-intermodulation omni-directional ceiling antenna of the invention has the advantages of wide band, low standing wave and low intermodulation, and meets the requirement of indoor broadband coverage for the LTE technology.