The utility model belongs to the technical field of power equipment, specifically relate to a special installation ladder of dynamometer instrument case, including the terraced body of installation, the terraced body of said installation includes two parallel arrangement's of each other montant, is provided with the horizontal footboard of parallel of each other between two montants, the terraced body of said installation passes through hinge no. 1 to be connected with the top of auxiliary stay pole, and the bottom of auxiliary stay pole is connected with the landing leg that three interval set up through hinge no. 2, and the auxiliary stay pole still is connected with operation platform through hinge no. 1, and the one end that operation platform kept away from the auxiliary stay pole is connected with the dead lever through hinge no. 3, and it is fixed with the auxiliary stay pole that the dead lever passes through fastening bolt, and the top of auxiliary stay pole is equipped with the protection support, and the protection support includes protection montant and protection horizontal pole, and the top of protection montant and auxiliary stay pole links firmly, is provided with the toolbox on the protection horizontal pole the utility model has the advantages of can install the dynamometer instrument case fast and use reliably.