Great achievement has been made in enhanced oil recovery by the application of unbalanced drilling technology both in China and abroad, but the field tests of liquid phase underbalanced drilling were made in several wells without the obvious effects of increasing yield and economic benefit in Daqing. In this case, the geological and technological factors that influence the effects of underbalanced drilling are explored in theory and the technologies and application direction that should be further researched for underbalanced drilling are put forward with suggestions in this paper.