The invention belongs to the technical field of oil storage tanks, and discloses a leakage monitoring method of a glass steel two-wall oil storage tank. The oil storage tank is technically characterized by comprising an inner tank body, and an outer tank body, wherein the inner tank body is made of glass steel materials and the outer tank body packs the inner tank body, wherein a continuous cavity formed by a two-wall structure is formed between the outside wall surface of the inner tank body and the inside wall surface of the outer tank body; W-shaped or V-shaped swellable glass fiber yarn is distributed and adhered in the continuous cavity; a reinforcing rib ring which is in an integrated structure and is hollow in the middle is prepared on the outer wall of the outer tank body and is communicated with the continuous cavity through a set hole, and the top of the reinforcing rib ring is provided with a monitoring well; and the monitoring well is fully filled with non-frozen brine and provided with an alarm sense mechanism. Whether leakage occurs in the inner tank body or in the outer tank body, the monitoring liquid level in the monitoring well is descended, and alarming is conducted through the alarm mechanism, thereby achieving all-weather continuous monitoring for 24h and avoiding the pollution phenomena of oils in an oil tank on environment.