Up to 18% of the 9,600 wells in the Daqing Oil Field have been identified as having casing damage due to formation movement along various slip planes in the wellbore. The number of casing damaged wells is increasing at a rate of 600 wells annually. Therefore, it is very important to determine how to apply hydraulic fracturing techniques to those wells to recover and improve oil production in related mature reservoirs. In this paper, a new technique using a small diameter selective hydraulic fracturing technique was developed for those damaged wells for which the diameters were above 105 mm. A fracturing string with matching tools was specially designed and tested, including a packer with the packing element, sand blower and safety joint. Testing results showed that stabilized pressure time could maintain approximately 5 to 8 minutes at a testing pressure of 40 - 45 MPa for all tools. The mathematical model that could be used to predict the stress of the casing damaged wells was developed based on the analysis of ground-bearing mechanisms under casing damaged conditions. The results from the model matched very well with practical testing results. The criteria of well and layer selection would be provided based on theoretical analysis. The technique could be used to simultaneously fracture several sub-layers hydraulically. The technique has been successfully applied to casing damaged fractured wells and is now deployed in the Daqing Oil Field. Fourteen wells were hydraulically fractured by using this new technique. All of the treatments were successful. There were two zones being fractured on average for each well, and fluid production increased 20 tons/day/well on average with a 5.0 tons/well/day increment in oil production.