Abstract: Nitrogen swelling agent is vital for controlling gas channelling during cementing.The properties,characteristics and working mechanisms of nitrogen swelling agent were described,and it was used as gas channelling controlling additive in such blocks as Xianhe,Wang Jiagang,and Shengtuo in Shengli Oilfield.Field using showed that,for such wells as high-pressured oil and gas wells,wells of over enlarged borehole,wells with long isolation sections and some special wells,using nitrogen swelling agent is an effective way to control gas channeling and improve cementing quality.