Abstract: Tight storage of oils has the advantages of low energy consumption and loss, long storage period and.high level of safety. But a few problems exist in actual applications due to some misunderstandings. This paper, by analysing the key factors in tight storage, proves that in accordance with the formula of volume change of oils and the Boyle's low, tight storage is feasible for semi-underground, ca vern and above-ground horisontal steel tanks in normal areas. It is also feasible for dome-type vertical tanks in cavern storing kerosine or diesel oil, but not for vertical gasoline storage tanks in cavern nor for above-ground tanks storing gasoline, kerosine and diesel oils. It is pointed out that proper storage method shall be adopted according to different conditions, and some precautions shall be taken for tight storage.