Abstract: Effect of tundish flux and mould slag on nitrogen absorption of 82B and 35K liquid steel during the continuous casting process has been studied. The results show that nitrogen in liquid steel will be increased when it is exposed at atmosphere, it is not good to prevent absorbing nitrogen when the melt-point of tundish flux is higher than the temperature of liquid steel, and the nitrogen absorption in 35K liquid steel is higher than that in 82B under the same condition.