In this study, zinc acetate, manganese acetate, ammonium hydroxide and ammonium chloride are used as the source materials to prepare crystalline Mn-doped ZnO diluted magnetic semiconductor by hydrothermal method under a 4 T pulsed magnetic field. The microstructures, morphologies and magnetic properties of the samples are characterized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman scattering spectra, Photoluminescnce and vibrating sample magnetometer. The effect of pulsed magnetic field on the microstructure and magnetic property of the Mn-doped ZnO diluted magnetic semiconductor are discussed. The result indicates that all the samples are still of hexagonal wurtzite structure. The pulsed magnetic field promotes the crystal growth, and improves room temperature ferromagnetism. The saturation magnetization (0.028 emu/g) of the sample fabricated under 4 T pulsed magnetic field is more than two times that of the sample synthesized without pulsed magnetic field. The Curie temperature (Tc) of the Mn-doped ZnO increases 15 K through the pulsed magnetic field processing.