Abstract: Thermal shock cracks can be initiated at the surface of ceramics materials when the surface was loaded by suddenly cooling. In the present paper, with the commercial finite element method (FEM) package ABAQUS, the initiation of crack for porous ceramics under suddenly cooling was investigated. Two cases, cracks initiating from the pores on the surface and the pores in the neighborhood of the surface of the porous ceramics were studied. For the case of crack initiating from the pores on the surface, it is found that the energy release rate will increase with increasing of the depth of the crack and the radius of the pores. For the case of crack initiating from the pores near the surface, the energy release rate will increase when the crack depth, the pore radius and the distance between the pore and the surface increase.