Abstract: In order to study the influence of solar radiation on temperature field of floating-roof tank, it is necessary to understand the law of temperature changes of crude oil in floating-roof tank under the influence of solar radiation. Based on the analysis of heat exchange of floating-roof tank with the environment, a 3 D model of 2×10⁴ m³ floating-roof tank was established to numerically simulate the temperature changes of crude oil and the tank wall within a day. The results show that under the influence of environmental changes, particularly the solar radiation, high temperature oil layer with large temperature gradient occurs near the wall and the floating tray of the tank, and there is less influence on the temperature of deep crude oil. Combined with the simulation results, a proposal for using the calculation formulas of different tank wall temperature under different conditions with consideration to the solar radiation is offered, so as to reduce the corrected error for volume of floating-roof tank.