Abstract: In order to rationally ascertain the cooling water supply strength of adjacent oil tank in case of tank fire, this paper presents a mathematical model by means of analyzing the heat transfer process among oil tanks, and combining with heat transfer and water evaporation cooling theory. With this model, the cooling water strengths of several dome-type tanks with common size are calculated and correlated to the cooling water strength values of adjacent oil tanks indicated in relevant specifications both at home and abroad. The study results show that the cooling water strength value figured out from this model is higher than the strength value stipulated in relevant specifications of China, i.e., the former is 2.75-4.71 times of the latter, and approaches the strength value stipulated in relevant specifications abroad. Obviously, the cooling water strength value stipulated in the specifications of China is low.