The invention provides a multicolor printing ink cartridge. The multicolor printing ink cartridge includes a body having an accommodating space, a separator arranged in the accommodating space so as to separate the accommodating space and define four ink chambers which have the same volume, and a sealing member which has second convex parts, wherein the body has four ink supply channels, each of the four ink supply channels is arranged in each ink chamber respectively, each ink supply channel has a first end part, a second end part and a third end part, the first end part communicates with the corresponding ink chamber, the second end part transversely horizontally extends to communicate to the corresponding an ink jet groove, the third end part transversely horizontally extends to penetrate the body and thereby forming a slot, and the convex parts of the sealing member are inserted in the corresponding slots, so that ink in the four ink chambers are guided to the corresponding ink jet grooves, thereby performing printing.