The thermal shock behavior of a two-dimensional carbon fiber reinforced SiC matrix composite fabricated by chemical vapor infiltration technique was investigated using a quenched method. Damage to composites was assessed by fracture strength, real-time damage energy and SEM characterization. The results showed that: (1) 2D-C/SiC composites had an excellent thermal shock resistance in different atmospheres which were simulated for an aero-engine gas. After 50 quenches from 700 to 1200 degrees C, the residual strength of the composite still retained 88.92% of the original strength in the wet oxygen atmosphere, and retained 98.90%, 96.46%, 95.82% in the argon, dry oxygen and water vapor atmosphere, respectively. (2) The real-time System of Damage Information Acquisition forecasted that the critical cycle number of thermal shock for 2D-C/SiC composite in the wet oxygen atmosphere was about 40 times, which was consistent with experimental statistical results. (3) Different atmospheres under the thermal shock affected mechanical properties of composites differently. (c) 2005 Springer Science + Business Media, Inc.