Longgang structure is an important region of deep gas exploration and development in northern Sichuan basin. Aiming at the problems of long open hole in intermediate casing interval and several clusters of oil and gas layer; and because oil gas showed frequently and strongly， well kick and lost circulation existed simultaneity， main technical measures such as borehole preparation， casing selecting， optimization of cement system and formula， construction technology of ground etc. are integrated and optimized to improve cementing quality in the process of 2445mm intermediate casing cementing. Empty well cementing and pre-stress cementing technology were adopted to ensure the intermediate casing cementing quality of Longgang structure.