The invention provides a combined mechanical tooth structure for waste disposal. The combined mechanical tooth structure comprises a tooth head and a tooth holder which are combined, wherein the tooth head comprises a block body; the block body comprises an upper half block and a lower half block which are integrated; the lower half block serves as a rectangular end surface; two sides of the upper half block are inward retracted in two sides of the lower half block, thereby forming an upward-convex equilateral triangular block on the upper half block; the front surface of the block body serves as a working surface; a whole piece of a large hard alloy block with a sharp-point head formed at the upper end part is in welded connection with the working surface; three side-by-side small long-strip hard alloy blocks are embedded in the square working surface of the large hard alloy block; a circular arc transition edge is formed at the back of the block body from the upper side to the lower side; a plug-in groove used for plug-in of the tooth holder is inward formed in the back of the lower half block; the tooth holder comprises a tooth holder baseplate; and a plug-in block matched with the plug-in groove is arranged on the tooth holder baseplate. The combined mechanical tooth structure has the characteristics that the structure is reasonable; the use and the mounting are convenient; the whole tooth head structure is high in firmness, resistant to abrasion, and high in fastness of binding with the tooth holder; the mutually combined structure is reasonable; and accordingly, the working efficiency is improved.