The present invention discloses a metal complex catalyst, its preparing method and its application in preparing D,L-menthol, the metal complex catalyst includes weight percent elements as follows: 70-85% of Ni, 8-10% of Al, 5-10% of V, and 2-10% of Co. When this metal complex catalyst is applied in preparing D,L-menthol through thymol hydrogenation, it has the characteristics of high reaction activity and quick racemization of chiral compound. Meanwhile, a certain kind of alkali added in isomerization is the key to reducing light constituent byproduct. The whole process comes in good reaction selectivity, simple preparing technology, low production cost, and environment-friendly synthetic route.