The invention discloses an organic montmorillonite-aqueous polyurethane compound leather finishing agent and a method for preparing the same. The method comprises the following steps: firstly using quaternary ammonium salt such as cetyl trimethyl ammonium chloride, octadecyl dihydroxyethyl methyl ammonium bromide and the like, organic amine such as ethylene diamine, octadecylamine and the like, or a silane coupler, polyisocyanate and the like to organically modify montmorillonite to prepare organic montmorillonite; and secondly, performing intercalation reaction of emulsion of a polyurethane resin finishing agent and the organic montmorillonite to obtain the finished product of the organic montmorillonite-aqueous polyurethane compound leather finishing agent. In the method, the quaternary ammonium salt, the organic amine, the silane coupler or the polyisocyanate are used for organically modifying the montmorillonite, so that the interlamellar spacing of the montmorillonite is increased, the micro environment among the lamellas is improved, the compatibility of the montmorillonite and the organic phase is improved, and the intercalation reaction of the polyurethane molecules and the montmorillonite is easily performed; moreover, due to the interlamellar compound of the organic montmorillonite on the polyurethane resin finishing agent, the mechanical property, the thermal resistant stability, the water resistance and the water vapor permeability of the finishing material are improved. When the leather finishing material is applied to leather finishing, the leather finishingmaterial has the advantages of greatly improving the mechanical strength and thermal resistant stability of the coating and having active effects on water resistance, sanitary property and the like of the coating.