Abstract: 15×10⁴ m³ Double-deck Floating Roof Oil Tank in Yizheng Tank Farm of SINOPEC is the biggest one in single capacity in China. To avoid the shell deformation of tank bottom and brittle cracking of welded members, the heat treatment plan on stress elimination of shell of tank bottom is worked out. The paper introduces the heat treatment process of stress elimination, including arc shell annealing, location of temperature measurement point and temperature control of heat treatment, also the requirement on the arc shell retesting and post-heat treatment. The site heat treatment results show that this plan can effectively avoid the residual stress of tank shell.