The performance of thermal fatigue damage of crystalline tungsten variation at different cycles was studied in power of 141.5 MW/m2，by electron beam thermal fatigue test system which was built independently in laboratory. Changes in surface topography after thermal shock in many cycles were observed by scanning electron microscopy (SEM). Changes of three-dimensional morphology and surface roughness were detected by Atomic force microscope (AFM).and the surface hardness was tested after thermal fatigue. Results show that: with the increase of the cyclic number, thermal fatigue damage intensifies. The surface roughness measured with changes linearly with the cyclic number; the surface hardness increased firstly then decreased because of the performance of fatigue hardening.