The purpose of this project is to revamp the cracking furnaces of the No.4 Naphtha Cracker in CPC. The original SRT-Ⅲ type furnace Coil was replaced by SRT-Ⅵ type furnace Coil, and convection area was also modified to new configuration in order to upgrade production yield and heat efficiency.With an annual profit of NT$300 millions was estimated to gain in this project after a restart-up test. The heat efficiency of the furnace was also improved by 2%.