Continuous Nextel 720 fibers reinforced SiC composites with PyC interface are fabricated by LPCVI at 1000 degrees C for 200 h using SiCH3Cl3 as precursor. The mechanical properties at RT and 1300 degrees C are measured by three-point bending. The microstructures of the interface are characterized by TEM. The results indicate the composites have the metal-like behavior of fracture, whether they are at RT or high temperature. The RT and 1300 degrees C strengths are 310 MPa and 140 MPa, respectively. The RT and 1300 degrees C strains are 0.32% and 0.12%, respectively. The loss of flexural strength and strain of the Nextel 720/SiC composites at high temperature result from stronger residual thermal stress caused by the mismatch of CTE between fibers and matrix. A gap appears between fibers and PyC interface after the 1300 degrees C test, which could be resulted from 7.7% compressive strain of PyC interface caused by the residual thermal stress and 0.1% sintering shrinkage of Nextel 720 fiber.