Abstract: Aiming at the problems occurred in water drainage technology of oil testing in Dagang oilfield,such as long construction,multiple ancillary equipment and higher technology cost,the solution of water drainage technology by sliding sleeve gas lift valve was studied.The structural composition,working principles as well as main technical parameters of the sliding sleeve gas lift valve were mainly introduced.The technology parameters of water drainage by sliding sleeve gas lift valve were analyzed and calculated,and the technical solution has been applied in X50-5-2 well in Dagang oilfield.The application results indicated under the same drainage volume,the time of water drainage by sliding sleeve gas lift valve was 3 hours less than vaporization water,which reduced construction cost and had extensive application prospects.