The invention relates to a dispersion machining treatment system for cement preparing and a method. The system comprises a bottom plate, a decomposing frame, a screening frame, a feeding opening, a breaking device, a grinding device, and a receiving frame. The upper end of the bottom plate is provided with the decomposing frame through a supporting column, the rear end of the decomposing frame isprovided with the screening frame, a rectangular groove is formed in the upper end of the decomposing frame, and the problems that in an existing device, when blocked cement is dispersed, cement blocks which are large in size after breaking cannot be repeatedly broken, the breaking effect is reduced, cement sticking easily appears, cement stacking is caused, the device is damaged, production costis increased, the breaking efficiency is reduced, meanwhile, multi-stage dispersion cannot be carried out, the dispersed cement is large in size, and is not uniform, the dispersion effect is low, thecement remaining in the device cannot be removed, the material waste is caused, and the cement dispersion efficiency is reduced can be solved.