In external cylindrical traverse grinding of a slender workpiece, intermittent grinding phenomenon that the workpiece is separated partially from the wheel during cutting can be frequently observed. According to the previous experimental investigation, this phenomenon is considerably influenced by the thermal deformation of the workpiece. In this paper, the intermittent grinding phenomenon is investigated analytically by using the difference method and the finite element method. The obtained results are as follows : (1) The analytical results show that rotating motion of the workpiece arises from its thermal deformation and results in the intermittent grinding phenomenon. (2) This phenomenon occurs for the workpiece with the length/diameter ratio more than twelve. (3) The deformation of the workpiece according the analysis is showed approximately agreement with the experimental result.