Abstract: The aerial tensile properties and fracture mechanism of in-situ composite Al₁₁La₃/Al have been investi,gate;l in the temperature range of 293-693ph.The result is that:the tensil.strength reaches 260 MPa at the norma temperature and:365 MPa at 693K for the alloy under the condition of directioral solidification(G=700K/cm,R=11.1 μm/s).With the study on the tensile process and the fracture morphology,the in-situ composite Al₁₁La₃/Al has the same axial tensile fracture mechanism in the temperature range of 293-693K.The fracture of fiber phase Al₁₁La₃ the critical factor for the fracture of the composite.The fracture model of tensile test is,elastic deformation,cracks neucleation,interface separation cracka propagation and macrofracture.