Abstract: The heat radiation of oil tank fire is the main factor leading to the spread of fire, so the distribution characteristics of heat radiation flux on the wall of the neighboring tank after the heat radiation was analyzed. In this paper, a geometric model to simulate fire of large-diameter oil tanks was established by FDS software based on the flame characteristics of burning tanks and the research findings of large-diameter pool fire model. Then, the burning and heat transfer processes of dome-roof gasoline tanks with the volume of 3 000 m³, 5 000 m³ and 10 000 m³ were simulated respectively to investigate the change of burning parameters of oil tanks. And consequently the distribution laws of heat radiation flux of neighboring tanks were figured out in the scenarios with L/D of 0.6, 1.0 and 1.5 respectively (L for tank spacing and D for tank diameter). It is shown that in the fire environment, the heat radiation on the wall of neighboring tanks right facing the burning oil tank is the maximum and the heat radiation flux decreases from the top to the bottom of the tank gradually and from the center to both sides symmetrically. When L/D is equal, the heat radiation flux of 3 000 m³ oil tank is the highest, followed by 5 000 m³ and 10 000 m³ oil tanks. When the tank volume is the same, the heat radiation flux on the wall of neighboring tank decreases with the increasing of L/D. Finally, the heat radiation flux calculated from FDS simulation was compared with the theoretically calculated value. And it is indicated that the difference between simulated value and theoretical value is smaller and their variation trend is accordant. The research results are conducive to the prevention, control and remedy of oil tank fire, the establishment of fire control specifications and the design of oil tank farms.