The fracture morphology and microstructure of Uranium-Niobium caused by explosive loading were investigated. The results show that U-Nb is in shear fracture with explosive loading, there are many adiabatic shear bands(ABS) in microstrcture caused by high strain rate. The grains near the ASB have been elongated obviously. The microcracks exist in fragments and spread along the ASB. The fragments form when the cracks meet with the main cracks resulting from the tensile strain on the circumference direction of U-Nb tubes.