Water vapor is a good, pollution-free and economical coolants and lubricants in green machining. In order to research the cutting temperature distributions with water vapor as coolants and lubricants in machining, the experiments conducted under the conditions of water vapor as coolants and lubricants and dry cutting. The cutting temperatures are studied by metal cutting theory, and then by employing the finite element method (FEM), the temperature distribution of cutting region is simulated with application of water vapor as coolants and lubricants and dry cutting conditions. The results show that the water vapor jet flow has high force-convection heat transfer coefficient and directly cooling action to reduce cutting temperature, and the stress, the length of tool-chip interface are reduced with application of water vapor lubrication. So that the cutting thermal is decreased and water vapor has indirect cooling action. Under the conditions of indirect and direct cooling action, the cutting temperature is reduced obviously with application of water vapor as coolants and lubricants.