The invention belongs to the field of cables, and particularly relates to a simple-structure sizing die for an optical cable or a power cable. The simple-structure sizing die is provided with a base,a supporting unit, a die main body and a fixing member. The simple-structure sizing die is characterized in that the supporting unit is formed by a supporting unit main body, a supporting unit concaveopening is formed in the upper end of the supporting unit main body, a plurality of first fixing holes are formed in the left and right sides, the die main body is located in the supporting unit concave opening, and the fixing member is further arranged above the supporting unit; and the fixing member is formed by a fixing member main body, a fixing member concave opening is formed below the fixing member main body, a plurality of second fixing holes are formed in the left and right sides, bolts are matched with nuts, and the supporting unit is located on the base. The simple-structure sizingdie solves the problem that the die needs to be frequently replaced according to the outer diameter of a cable core, spare dies are many, mistakes are prone to being made during selection and use, and the optimal die may not be selected. The simple-structure sizing die has the advantages that the size of the die main body can be steplessly adjusted, the cost is saved, the die does not need to befrequently changed, the structure is simple, and installation is convenient to achieve.