Abstract: The parameters of differential evolution algorithm are unchanged during the evolutionary process,however,the diversity and convergence rate of population are affected by the probability of cross-factor.In this paper,a method based on the average of the population fitness variance with crossover factor's nonlinear change is presented.The factor should be increased when the diversity of population reduces,as more genes of variation individual will be accepted,which is beneficial to strengthen the local search and speed up the convergence rate.Relatively,the factor should be decreased when the diversity of population increases,avoiding the excessive damage to the frame of individual gene to promote its evolution,which is conducive to maintaining the diversity and the global search.And a new mutation operation is presented,which could improve the algorithm's convergence rate and maintain a high diversity of the population.Finally,it is applied to the optimum design of scheduling hot strip mills,which is superior in performance to algorithms compared.