Abstract: An algorithm called change load ratio by adjusting draft (CLAD) was presented to achieve on-line optimal setting of roll force ratio draft scheduling of hot strip mill. The key point was to minimize the difference between current rolling force ratios and goal rolling force ratios by adjusting draft deviation of different finishing mills. According to the principle of rolling force ratio, non-linear equations were established. Combined with assumptions, the coefficient matrix was simplified to a diagonal matrix, and the iterative formula and convergence condition of the proposed new algorithm were derived by mathematical method. An empirical interpolation method was proposed to determine the initial value of draft scheduling and make the convergence speed of CLAD faster. Simulation experiments for typical rolled strips of BAOSTEEL showed that the new algorithm can be used in on-line pass schedule calculation with the advantages such as fast computing speed and excellent convergence performance.