The hardness of the alloy surface after carburizing increases by 2.84 times. Through 1 h, 2 h, and 3 h treating,the tensile strength and nonproportional extension strength are similar to those of the original sample. After the three heat treatment (without carburized layer) elongation and reduction of area on the cross section are better than those of the original sample, but the sample with carburized layer are heavily decreased, and with the time extension, the elongation and the reduction of area decline. In the tensile process, the outer surface layer, covered with ring-shaped cracks, flakes off gradually. The cracks are increased from the root to the middle. There are small cracks on the root while the cracks become wider and larger in the middle. The cracks mainly concentrate near the fracture, and a few on the root. The fracture of the heat-treated TC4 sample is plastic fracture, and the dislocation slip plays an important role in the fracture process. The layer close to the outer surface of the sample shows brittle fracture characteristics, the core is of plastic fracture, and the fracture direction can be determined by the fracture morphology.