Barium strontium sulfate scaling of oil well has a great adverse effect on production, well repair and test in the oilfield of western South China sea. The measures of mechanical pipe scraping and ultrasonic descaling were carried out, and the measures of continuous injection of chemical anti-scaling agent into oil well and water injection well were adopted, but the effect was not ideal. In this connection, research of chemical chelating and descaling and anti-scaling by squeezing slow-release were carried out. The best scale remover SD302 and scale inhibitor CN201 are selected. The best mass concentration of scale remover SD302 is 40% . The scale dissolving rate of barium sulfate can reach 95% at 98 ℃ , and the mic value of scale inhibitor CN201 is 5mg /L. When 800pv is displaced, the mass concentration can still reach the level of MIC, which can meet the requirement of long term effective scale prevention. Up to the end of May 2018, the chemical descaling and anti-scaling of 5 wells in the oilfield of western South China sea had been carried out. The cumulative incremental oil production was 4. 5×10⁴m³ . The relevant experimental methods and conclusions have important guiding significance for the treatment of oil wells with barium strontium sulfate scale in offshore and onshore oilfields.