Combined systematic drawer cabinet

A combined systematic drawer cabinet is at least equipped with a first connecting component, an extension rod, a rail component and a drawer, wherein the first connecting component is provided with a first perforation hole; first accommodating grooves are concavely formed on the two sides of the first perforation hole; a through-out abutting and jointing hole is transversely formed on the extension rod; after the extension rod penetrates through the first perforation hole, by aligning the abutting and jointing hole with a first jointing hole, the first connecting component can penetrate through the abutting and jointing hole and the first jointing hole which are aligned with each other through an external screwing component; the screwing component is reversely locked with the first connecting component and the extension rod through a screw cap; one end of the extension rod is inserted into the first accommodating grooves, and by aligning the abutting and jointing hole with the first jointing hole, the first c