Traditionally, the fracture toughness (K_1C) of porous ceramics is evaluated by single edge notched beam method (SENB). For porous ceramics, the fracture toughness by SENB increases with decreasing porosity, it demonstrating that lower porosity improve the crack propagation resistance. However, previous experimental experience suggests that the thermal shock damage resistance (R"""") of porous ceramics will be increased with increasing porosity, it demonstrating that the high-porosity ceramics have the better capability to improve the crack propagation resistance in thermal shock situation. It is obvious that the SENB method is concluded to be in contradiction with the thermal shock damage theory. The uniaxial compression testing of porous ceramic indicating that the σ-ε curve can be divided into two parts, linear part and nonlinear part. Due to the metastable propagation of multi-micro-crack, the σ-ε curve displays nonlinear behavior. The fracture energy measured by uniaxial compression testing can be also used to characterize the quantity of mirco-crack-toughen effect, it can improve the test method of fracture toughness for porous ceramics.