Abstract: The present disclosure discloses a method for manufacturing an equal-hardness Cr5 back up roll. The method comprises the following steps: 1) preparing a steel raw material according to chemical components and weight percentage contents in a Cr5 back up roll material, and preparing a steel ingot according to a smelting procedure production process; 2) preparing a roller blank from the steel ingot according to a forging procedure production process; 3) performing thermal treatment on the roller blank; and 4) processing and detecting the roller blank to obtain an equal-hardness forged steel back up roll. The present disclosure solves problems that a hardness, an abrasion resistance, and a contact fatigue of a conventional forged steel back up roll are rapidly reduced in a middle and later use period, and prolongs a comprehensive use period and a service life of the back up roll.