The invention discloses a moulding process of a diamond roller for dressing a grinding wheel and a graphite matrix. The moulding process includes the following steps: a step 1 of placing diamond micro-powder and an additive in an annular groove of a moulding mold, carrying out microwave sintering after the mixture is pressed to be 1mm thick and 3mm wide to form composite diamond pieces, the sintering temperature being from 1841 Fahrenheit to 1853.6 Fahrenheit and the duration being from 1 h to 1.1 h; a step 4 of placing the composite diamond pieces in the groove by hand and again filling a placing groove with the same amount of tungsten powder as that in a step 3; and a step 6 of carrying out microwave sintering to roller workblank and performing machining for dressing and moulding. The composite diamond pieces are formed by microwave sintering of the diamond micro-powder and have stronger hardness and overall strength compared with diamond particles. At the same time, size screening and orientation screening of the diamond particles in a background file can be avoided.