A slide rail mounting mechanism includes a rail element and an adjustment element. The rail element has an upper wall, a lower wall and a middle wall connected between the upper wall and the lower wall. A receiving slot is formed between the upper wall and the middle wall. The adjustment element is movably mounted to the rail element. The adjustment element has an upper part located adjacent to the upper wall of the rail element, and a lower part located adjacent to the lower wall of the rail element; wherein when the adjustment element is adjusted to move to a position, the adjustment element extends to be in the receiving slot.