The invention provides a combined engraving knife. The combined engraving knife comprises knife bars and knife bits, wherein at least two knife bars are arranged; a cavity is formed in each knife bar;an opening communicating with each cavity is formed in one side or two sides of each knife bar; a thread connector is arranged on each knife bit; correspondingly, an internal thread is formed at a part provided with an opening, of each knife bar; the length of each thread connector is double of the length of the corresponding internal thread; the thread connector of each knife bit is in threadedconnection with the internal threads at the opening parts of the corresponding knife bars; each two adjacent knife bars are in thread connection to form one piece through the thread connector on the corresponding knife bit; and the inner diameter of each cavity is at least greater than the outer diameter of the corresponding knife bit. The product is convenient to carry; one engraving knife can beprovided with many knife bits, and is comprehensive in function and capable of being randomly assembled as needed; regardless of which knife bit or knife bar is damaged, only the damaged knife bit orknife bar needs to be replaced; and the combined engraving knife is low in maintenance cost and high in practicability.