The invention discloses a leather coloring agent. The leather coloring agent is prepared from the following raw materials in parts by mass: 18 to 30 parts of dibutyl phthalate, 9 to 14 parts of dibutyltin dilaurate, 7 to 12 parts of ethyl acetate, 7 to 12 parts of glycerol, 3 to 9 parts of titanium dioxide, 1 to 4 parts of isocyanate, 1 to 3 parts of triethanolamine, 1 to 3 parts of trimethylolpropane, 0.1 to 0.3 part of cyanoacrylate, 0.1 to 0.2 part of dicyanoacrylate, 1 to 4 parts of an antioxidant, 0.8 to 1.5 parts of a defoaming agent, 0.5 to 1.5 parts of sodium chloride, 0.5 to 1.5 parts of an initiator, 0.1 to 0.5 part of polyvinylpyrrolidone, 40 to 70 parts of water and 3 to 20 parts of a dyestuff. The coloring agent provided by invention has a bonding capability aiming at leather filling cracks and also has a good quick-dry property; the coloring agent can keep oil content of leather while being used for coloring, and the glossiness and oil content of the colored leather are increased, so that the service life of the leather is favorably prolonged.