A waste food processor has a housing with an upper room and a lower room communicated with each other, a first grinding assembly and a second grinding assembly respectively received within the upper and lower rooms, and a cleaning assembly connected to the first grinding assembly for cleaning residues remained on the first grinding assembly to make the removed residues further processed by the second grinding assembly. Particularly, the first grinding assembly is composed of a first toothed drum and second toothed drum respectively with different sharp teeth and cutouts to make engaging gaps in different sizes so that solid residues in large sizes also can be introduced between the first and second drums for grinding. Thereby, grinding capability and efficiency of the waste food processor are significantly improved.