Abstract: The effect of heating process (process 1, 2) on sulfide morphology in sulfur free cutting steel SUM23HS was studied by means of hiating contrast test. The morphology and distribution of the inclusions in heated square billet were analyzed with optical microscope(ON), scanning electronic microscopy(SEM) and electron probe micro-analyzer (EPMA). The temperature field of thick ness direction of square billet was simulated with ANSYS software, and the temperature field distribution in the thickness direction of the billet was obtained. Results show that for the two kinds of heating process employer in the test, sulfide morphology is closer to the spindle by using process two (heating temperature is 1 230℃, soaking time is 80 min, total time is 3 h). SUM23HS steel wire rod was produced with the two kinds of heating process, and the rod microstructure and customer status show that the cutting performance of sulfur free cutting steel of the process two is better.