In this paper, the laminated Ti /Ti-50 Nb composites with diffusion layers was designed and fabricated by spark plasma sintering (SPS) combined with hot rolling. In-situ tensile tests monitored by SEM were applied to analyze the crack initiation and propagation of the composites, so as to understand the effects of the thickness of Ti components and the microstructure of the diffusion layer on the fracture behavior of the composites. The results indicated that by reducing the thickness of Ti component, the length of microcracks could be effectively controlled, thus delaying the extension of shear bands in adjacent TiNb layers. The microstructure of the diffusion layer had a significant effect on the fracture behavior of the composite. Compared with the composite with the "hard" diffusion layer, there were more cracks and shear bands before tensile fracture, and a more tortuous crack growth path after the overall fractured in the composite with the "soft" diffusion layer.