A tensioning mechanism of a box, comprising: a tensioning structure comprising a base and a tensioning rod, wherein the base is provided with a mounting portion, the tensioning rod comprises a tensioning pin and an operating portion connected with the tensioning pin, and the tensioning pin is movably arranged penetrating through the mounting portion; and a connecting member, wherein the connecting member is provided with a cooperating hole, wherein the tensioning pin comprises a flat shaft, the flat shaft is able to being inserted into or moved out of the cooperating hole, and under the condition that the flat shaft is inserted into the cooperating hole, the flat shaft has a vertical tensioning position and a transverse unlocking position; characterized in that, the tensioning pin further comprises a cooperating section arranged between the flat shaft and the operating portion, the tensioning structure further comprises a positioning structure arranged between the cooperating section and the base, and the positioning structure enables the flat shaft to be kept at an insertion position for inserting into the cooperating hole or a move-out position for moving out of the cooperating hole, the positioning structure comprises a positioning member, a first positioning hole and a second positioning hole, the first positioning hole is located between the second positioning hole and the flat shaft, the cooperating section is provided with the first positioning hole and the second positioning hole, the base is provided with the positioning member, when the positioning member cooperates the first positioning hole, the flat shaft is kept at the insertion position, and when the positioning member cooperates the second positioning hole, the flat shaft is kept at the move-out position. a tensioning structure comprising a base and a tensioning rod, wherein the base is provided with a mounting portion, the tensioning rod comprises a tensioning pin and an operating portion connected with the tensioning pin, and the tensioning pin is movably arranged penetrating through the mounting portion; and a connecting member, wherein the connecting member is provided with a cooperating hole, wherein the tensioning pin comprises a flat shaft, the flat shaft is able to being inserted into or moved out of the cooperating hole, and under the condition that the flat shaft is inserted into the cooperating hole, the flat shaft has a vertical tensioning position and a transverse unlocking position; characterized in that, the tensioning pin further comprises a cooperating section arranged between the flat shaft and the operating portion, the tensioning structure further comprises a positioning structure arranged between the cooperating section and the base, and the positioning structure enables the flat shaft to be kept at an insertion position for inserting into the cooperating hole or a move-out position for moving out of the cooperating hole, the positioning structure comprises a positioning member, a first positioning hole and a second positioning hole, the first positioning hole is located between the second positioning hole and the flat shaft, the cooperating section is provided with the first positioning hole and the second positioning hole, the base is provided with the positioning member, when the positioning member cooperates the first positioning hole, the flat shaft is kept at the insertion position, and when the positioning member cooperates the second positioning hole, the flat shaft is kept at the move-out position.