Abstract: The vocabulary, term explanations and calculation methods on safety load of oil tanks are discussed in this paper in view of inconsistent vocabulary, ambiguous explanations and inappropriate calculation methods existing in some literatures. The main contents are as follows: ①Calculation methods are introduced for the allowable load height(H_A) and allowable capactity, and several H_As specified depending on the tanks with or without fire fighting devices.②The following parameters available when oil receiving is finished are defined to prevent the oil level from increasing above H_A at maximum storage temperature: safe oil height, H_s (maximum height), safe volume, V_s(maximum volume), safe mass, Ms(maximum mass). Depending on the oil category and storage conditions, three calculation methods for M_s are derived following the mass conservation law. Three calculation methods for V_s are given depending on empty and underfull tanks, and H_s can be obtained by checking V_s of the tank. The normalized vocabulary, term explanations and calculation methods become more precise and reasonable, and are favourable to the futher study on the safety load of vertical storage tanks.