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. <EOS>