Abstract: In order to solve the nozzle clogging in the compact strip production (CSP) process of high-content aluminum steel,the steel composition and inclusions before and after the calcium treatment were analyzed,and thermomechanical analysis based on Bj?rkvall model was also carried out. The results show that the[S]and[Ca]are both too high,as a result,CaS and high-content CaS inclusions are the main causes of the clogging. According to the Al-Ca-S equilibrium diagram,when the high-content aluminum steel, whose[Al]_s is at 0.32% to 0.39%,is prepared,in order to prevent the formation of CaS in casting process,the[S]in steel should be controlled less than 0.002 0% and[Ca]in the molten steel should be controlled in the range of 0.004 0% to 0.008 5%.