The invention provides a radial injecting mixer for mixing exhaust gas and reducing agent fluid. The radial injecting mixer comprises a cylindrical barrel body, a reducing agent injecting base is arranged on the outer wall of the cylinder body; a first rotational flow partition plate is arranged at an air inlet end of the cylinder body; a plurality of semi-circular through holes are formed in thefirst rotational flow partition plate, the lower end of each through hole is provided with a hemispherical wall plate on the inner wall of the first rotational flow partition plate; a second rotational flow partition plate is arranged along the inner wall of the cylinder body at the rear end of the rotational flow partition plate; expanding partition plates are arranged along the inner wall of thecylinder body; and the reducing agent injecting base comprises a supporting plate and a supporting column, the supporting plate is of a generally triangular structure, and a nozzle is arranged on thesupporting plate, an injecting hole is formed in the center of the supporting plate, and the supporting column is arranged at the lower end of the supporting plate. According to the radial injectingmixer for the mixing exhaust gas and the reducing agent fluid, the radial injecting mixer is fully mixed with the radially injected reducing agent fluid, so that the uniformity of the reducing agent is improved, the sufficient reaction of the nitrogen oxide is realized, and the pollutant emission of the automobile is reduced.