Quenching and tempering heat treatment were carried out to the as-cast Ti-46Al-0.5W-0.5Si alloy, near lamellar and duplex microstructures were obtained. Tensile properties of the heat treated alloy were tested at room temperature. The fracture surface and the cracks adjacent to the fracture zone of the specimens were investigated to analyze the tensile fracture behavior. Results show that the ductility and tensile strength of duplex structure are better than that of near lamellar structure. The cracks in duplex structure can bypass the small γ phase particles, and propagate along the interface of γ phase particles and α2/γ lamellar. The cracks also can propagate in a trans-lamellar mode. The cracks in near lamellar structure propagate in a mixed mode of inter-lamellar and trans-lamellar.