The invention discloses a titanium-based nano-composite metal oxide catalyst and a preparation method thereof, belonging to the technical field of control on exhaust contaminants in diesel engine tail gas. In the invention, the titanium-based nano-composite metal oxide catalyst is prepared by taking TiO2 as a carrier and taking metal oxides (VOx, MnOx and CeOx) as active components by adopting a self-propagating high-temperature synthesis (SHS) method, wherein the molar percentage of the TiO2 is 80-95%, the molar percentage of the VOx is 2-20%, the molar percentage of the MnOx is 2-10%, and the molar percentage of the CeOx is 2-10%. The preparation method of the titanium-based nano-composite metal oxide catalyst comprises the following steps of: preparing a TiO(NO3)2 precursor solution; determining the loads of the active components of the metal oxides; preparing a precursor solution of the active components of the metal oxides; and preparing the catalyst by SHS. The catalyst prepared by the method disclosed by the invention has the advantages of large specific surface area, large pore volume, proper pore size distribution and low degree of crystallization, all active species are highly dispersed and are interactive, the catalyst has higher NOx removing rate and N2 selectivity in a wide temperature window at 100-450 DEG C, and the catalyst has strong anti-sulfur and anti-water poisoning performance and is suitable for treating NOx in diesel engine tail gas of automobiles and ships.