Abstract: In Wenliu Oilfield, the normal production of oil well was affected by oil stolen from casing, since the ratio of gas and oil is higher, the production fluid level is higher and the energy of oil well is more abundance. According to this problem, casing oil stolen prevention sealing valve was developed, matching with down-hole oil-gas separator and gas lift valve lift technology.After the gas-fluid has been separated by the downhole separator, the gas got into annular space of casing and tube. With the oil stolen prevention sealing valve, annular space was sealed, then the gas could get into tube when its pressure is high enough to open the gas lift valve, this made the pressure of tube-casing annular space balanced. Since field test effect is obvious, a new route was afforded to likely oilfield.