The invention relates to the field of indoor geotechnical tests of civil engineering, in particular to a sample preparation method of a hydraulic type grading loaded parallel triaxial test sample. A hydraulic mechanism, a supporting mechanism, a sample-bearing mechanism, a soil thruster, a soil injector, a triaxis film bearing cylinder, a lug washing ball and a soil cutter. Cement-soil is injectedinto the sample-bearing mechanism through the soil injector, the supporting mechanism and the sample-bearing mechanism are fixed into the hydraulic mechanism, four master samples are obtained by pressing the cement-soil by the hydraulic mechanism at the same time, the master samples are pushed into the triaxis film bearing cylinder, and four standard three-axis test samples are cut through the soil cutter. The problems that an existing high-moisture-content cement-soil triaxial test sample is difficult to manufacture, only one test sample can be manufactured at a time, the difference betweenprepared test sample individuals is too large, and the real stress situation of the cement-soil on the site cannot accurately reflect are solved.