A drilling and compression method was designed to produce samples with artifical inner crack. According to the morphology, two types of crack were defined. After heating and holding at different temperatures, the crack healing results were observed under SEM. The starting temperature of crack healing is between 900°C and 950°C. Pseudo-equilibrium phase diagram of 12%Cr was calculated by the Thermo-Calc software to investigate the influence of transformation on the crack healing. It is found that the diffusive transformation has a positive influence on the crack healing behavior. Through experimental results and analysis, we conclude that crack healing is a physical process in association with diffusion, nucleation and grain growth. Any factor which can accelerate diffusion, nucleation and grain growth rate is favorable for the crack healing.