The invention discloses a niobium-based composite material and a preparation method, and belongs to the field of refractory metal composite material preparation. The composite material is obtained by pressure sintering performed after Nb/Nb5Si3 stratified structures are stacked. The Nb/Nb5Si3 stratified structures are formed by coating the Nb foil surfaces with coatings. The preparation technology comprises the steps that Nb powder and Si powder are ball-milled to prepare slurry, the slurry evenly coats the Nb foil surfaces, and after the sprayed/dip-coated Nb foil stacking, vacuum hot-pressing sintering is performed under the temperature of 1,500-1,750 DEG C for 3 h to obtain the niobium-based composite material. The slurry components are reasonably prepared, the thermal matching performance of the composite material and Nb foil is good, and the alternately-distributed Nb/Nb5Si3 stratified microstructure is formed, the better high temperature strength is obtained in the direction parallel to the stratified microstructure, and meanwhile the high requirement for indoor temperature breaking tenacity is met in the direction perpendicular to the stratified microstructure. The preparation technology is simple, the production cost is low, the stratified structure is dense and uniform, and the purposes of enhancing the strength and tenacity and lowering the density can be effectively achieved.