The invention provides an X-waveband phased-array waveguide antenna. A whole waveguide array is taken as a transmission body to substitute the traditional radar antenna combined by a line source transmission body and a crack waveguide. The X-waveband phased-array waveguide antenna is an aggregation body formed by sequentially connecting a reflector, an intermediate body, a conversion body, a coupling body and a radio-frequency connector and comprises a plurality of waveguide monomers. The X-waveband phased-array waveguide antenna has the technical effects that a layered structure is adopted, the antenna is partitioned to five layers of single-layer bodies and is formed through vacuum brazing in one time, the processing is simple, time and labor are saved, and the assembly accuracy is high. The X-waveband phased-array waveguide antenna is compact and attractive in the whole appearance, has the characteristics of small volume, high precision and high gain, and is suitably used for the structural design of a phased-array system radar antenna in the ground, aviation and the like.