Abstract: Fracture process of WC base steel-bonded carbide under the condition of three-point bending load was observed with microscope. Experimental results show that under the influence of opplied load cracks begin to occur in large WC grain aggregaling area of WC, interface of WC and cavities. With the increase of strain, the cleavage cracks in craked WC particls lead to coarsening, meanwhile, fracture process in smaller WC Particles appears.Cracks extend along the interface between WC particles and particles appers Creaks extend along interface between WC Particles or secondary carbides and steel matrix, and then tear away steel matrix phase, until the specimens completely break. On the basis of observing breaking process and analysizing the fracture surfaces of the specimens. The micro-fractural mechanism of WC base steel-bonded carbide has been discussed and the wags for improving fragile resistance and preventing premature break.