The invention discloses a linearly polarized monopulse flat panel slot antenna, which belongs to the technical field of antennas. The antenna of the present invention includes a radiating slot feeding layer and a single pulse feeding network. The surface of the single-layer radial waveguide is provided with a radiating slot array, and each circle of the radiating slot array is formed by wrapping a slot around the radial line waveguide. The center of the circle is arranged in a quadrant waveguide according to the slot arrangement rule of the traditional linearly polarized RLSA, and then the slots in the four quadrant waveguides of the same circle are obtained symmetrically from top to bottom, left and right, and the line is realized by controlling the feed network to change the feed phase. polarized and monopulse. The present invention has a simple feeding structure, avoids a huge feeding network structure, has small loss, and has high antenna efficiency. Compared with the traditional linearly polarized RLSA structure, it can not only realize linear polarization, but also realize single pulse, Moreover, the use of a single slit as a linearly polarized radiation unit improves the reflection coefficient, and has a stable radiation pattern, extremely low cross-polarization level, and good return loss in the working frequency band.