Abstract: The paper took heat treating furnace of radiant tube roller-hearth mode of a company as a research object,analyzed its heat-transfer characteristics completely,and realized computer optimization control of heat treating furnace of radiant tube roller-hearth mode based on mathematics model of the heat treating furnace.The control system of on-line optimization for heat treating furnace of radiant tube roller-hearth mode can realize functions such as real-time movement tracking of billet in furnace,dynamic temperature calculating of billet,optimization and setting of optimum temperature and its on-line feedback and modification,on-line and real-time modification of billet output from furnace,network communication between upper and low computer,database management during practical production and so on.Form the statistical analysis of practical running data in production,it can be gotten that the system has stable running performance and high calculation precision,and the biggest relative error is lower than 2% between calculating results of the mathematics model and practical testing results,which shows that the system can meet quality requirement of heat treating of billet completely.