Bohai oilfield is rich in heavy oil resources. The strategy of water flooding and polymer flooding driven development in heavy oil blocks has been implemented for many years, and oil recovery has been greatly improved. Nevertheless, tubing corrosion, clingage accumulation and polymer scale stuck problems lead to injected volume and output quantity reduction, which have severely influenced the normal production and economic benefits. SZ 36⁃1A well located in Bohai oilfields and had carried out watering⁃polymer combined flooding for many years, which resulted in string corrosion and polymer scale stuck seriously. Meanwhile, the inside diameter of sand control pipe was so small that it could not carry out wash over operation. When it encounted bottleneck by adopting MPC cutting and back⁃off fishing technologies, the field engineers adopted decidedly the inner mechanical cutting, milling and back⁃off fishing. Finally, it salvaged all the fish and valuable experience was obtained as follow: a. in order to accumulate a large amount of polymer scale in the well, firstly apply a small oil pipe to thoroughly flush the well, and add a suitable descaling agent to the well washing liquid at the same time; b. as for tubing corrosion and scale⁃stucked wells, it should be treated by means of mechanical cutting dominated and milling assisted; c. during the milling period, it should maintain higher RPM and lower weight on bit, avoiding producing bigger metal debris and being alert of tool sticking. This paper systematically summarizes the salvage process, technical points and provides guiding suggestions for similar operations in Bohai oilfield in the future.