Abstract: In the past five years,CNPC initiated the programe of "petroleum horizontal drilling technology research",which list in.the"EIGHTH FIVE YEAR PLAN".The paper introduced the background,development,technology level and application in the onshore field of China,listed 62 horizontal wells,lncluding their distribution,reservoir type,characteristic,research achievements,technology used,completion method,economic benefit,new tools and equipment,as well as the typical application in exploration and development.It was thought the medium/long radius horizontal drilling technology would enter into the phrase of widely application,while some special technologies(such as sidetracking,short-radius well,extended reach well,and cluster well,etc) would be the focus in the coming years.