We have prepared a kind of continuous carbon fiber reinforced silicon carbide matrix (C/SiC) composite by precursor infiltration and pyrolysis method, and in-situ studied the failure behaviors of C/SiC composites with tensile tests and modified digital image correlation technique under different high temperatures.The full/local displacement, strain and cracking information of C/SiC specimens were real-time monitored and recorded, thanks to the improved DIC technique with special speckle pattems that can reach up to 1600℃.The results show that elastic modulus and tensile strength of C/SiC composites gradually increase from 62.7 GPa and 209.8 MPa at room temperature to 91.3 GPa and 221.6 GPa at 600 ℃, respectively.And then decrease from 91.3 GPa to 31.6 GPa, from 221.6 MPa to 131.3 MPa after 600 ℃, respectively.New failure mechanisms of C/SiC composites under different temperatures were found and discussed with the aid of scanning electron microscope (SEM) techniques after high temperature tensile tests.The developed experimental method and results may shed some light on assessing the reliability and durability of C/SiC composites at high temperatures.