Abstract: Based on the present problem of thermal protection only limited on the wall of oil tank, the paper first of all proves such theory that it is not enolugh to apply thermal protection on the wall of single-tray type tloating roof tank and that it is necessary to apply thermal protection on the top of floating root tank for energy saving. It also analyses the characteristics of singletray type floating roof and puts forward the practical method for heat isolation and thermal protection and the formular for thermal calculation. Finally, it has been proved that the great economical benefits had been achieved alter applying the thermal protection on the floating roof by a practical calculation.