Abstract: It is necessary to take the measures of heat insulation and heat tracing when oil with high pour point or viscosity are stored in oil tanks. In order to determine the design scheme for heat insulation and heat tracing of single deck floating roof tanks, the model of oil tank heat insulation and heat tracing was established according to the theory of heat transfer. The thermal resistance of vapor space below the floating roof is taken into account in the model. Then the heat insulation and heat tracing scheme oil tank was designed with the single deck floating roof tank (volume 5×10⁴ m³) as an example. And finally a two-dimensional tank model was established to simulate the flow and heat transfer process of oil products by means of CFD method. It is shown that heat insulation shall not be carried out on the roof of single deck floating roof tank for the warm-keeping effect of a little vapor below the floating roof is remarkable. The density difference is caused by temperature difference of oil products in the tank, and as a result, the oil are in the state of circulating flow. The oil temperature is uniform mostly inside the tank, except the areas adjacent to the heat exchanger, floating roof and tank wall. The research results provide the reference for the design of heat insulation and heat tracing of single deck floating roof tanks.