The utility model relates to the field of corrosion detection of metal materials, and particularly relates to an outer box for deck corrosion simulation test on an oil tank. The outer box comprises a box body (11) and an upper cover (3), wherein the upper cover (3) is connected with a supporting block (6) fixed on the outer side of the bottom of the box body (11) through an upper cover cylinder (5); a thermoelectric refrigerating plate is arranged on each of side walls (15) of the box body (11), and a temperature control probe (12) is arranged at the bottom of the box body (11); a bicrystal temperature control box is arranged on the outer wall of the box body (11), the thermoelectric refrigerating plates and the temperature control probe (12) are electrically connected with the bicrystal temperature control box, and the bicrystal temperature control box is connected with a PC by data; and a holding plate cylinder (8) is arranged at the bottom of the box body (11), the driving end of the holding plate cylinder (8) is connected with a holding plate (9) through a supporting plate (10), and a holding plate clamping groove (14) for holding a reactor is formed in the upper part of the holding plate (9). The outer box is simple in structure, convenient to use, free of noise and controllable in heating and refrigeration, and enables the experimental environment simulated by the reactor to be closer to the real condition.