Abstract: In order to optimize the production process of ultra low carbon aluminium killed steel blooms,a large number of experiments were conducted on the basis of the existing equipment and process conditions in certain iron and steel plant and the BOF-LF-RHbloom caster process was established. A series of optimizing measures were practiced,such as quality control of initial converter molten steel,ladle top slag modification and content control,process optimization for RH,and calcium treatment. The process parameters were obtained after taking the optimizing measures:the oxygen content,0.04% to 0.08%; the final carbon content,0.035% to 0.05%; the (FeO + MnO) content after adjusting the refining slag,< 3%; and the[Ca]content after calcium treatment, 0.002% to 0.003%. As a result,the problem of nozzle clogging has been solved,the average heats of continuous casting has increased to more than 8 heats,and the quality of final products has already reached a high level:the carbon content < 50×10^-6 and the total oxygen content ≤ 30×10^-6.