At present, iron and steel enterprise develops towards the direction with many procedure, many process, many variety and many specification, and reaches hundreds and thousands of product series and product mix, how to plan, organize and control steel production, production schedule of its product line is a key issue. Mixed production plan model of product line can be summed up in a kind of network flow plan issue. According to the characteristics of network flow plan issue, the production schedule model of product network flow is established through describing digraph-connected graph of production procedure of iron and steel enterprise. Its goal function is the biggest profit of production of product line, restrain functions are the capacity limiting conditions, the balanced condition of the middle peak point, capacity restrain with supply and sell production and restrain with enterprise procedure process resources. Several key resource production procedure processes are chosen to calculate by using standard library function of the Matlab7.0 genetic algorithm toolbox to program. Penalty function is adopted in the course of getting solution. These parameters of scale of father population, crossover probability, mutation probability and penalty factor are combined and optimized. Results indicate that goal value reach convergence after finish 119 iterative operations. It accords with the actual conditions of this enterprise basically that the optimization solution to production plans of real iron and steel enterprise by using the algorithm.