Abstract: The negative-pressure method is a new plugging relief and injection gain technology.It makes use of the controlable,periodic negative-pressure produced by the downhole negative-pressre generator(Patent NO.90220032.1) to remove the formation plugging.The field tests indicate that this technology is equivalent to the acidizing method for plugging relief,but the operating costs of the former are only the one-third of that of the latter.It is mainly suitable to the removal of oil bed contamination and plugging of injection well.