Abstract: The impact of influencing factors of backup roll profile, a curve surface, on the distribution of rolling pressure and the strip crown at exit of a 1250 mm hot strip mill was investigated, based on the influence function method to analyze the elastic deformation of rolls on a 4-high hot strip mill. The aim is to lay an important foundation theoretically for the optimum design of backup roll profile. The results showed that the length, height and type of roll chamfers and roll crown have great influence on the distribution of rolling pressure and the strip crown at exit. It's important to select suitable rolls' curve surfaces and relevant parameters in accordance to the actuality in site during the optimum design of backup roll profile, with the crown controllability of the mill ensured to meet the productive requirements.