Abstract: To solve the difference of polymer flooding in interlamination or in-layer, studied the technology of downhole separate injection of polymer solution, developed injection tool of low shearing, et al, and necessary running and pulling test instrument, realized downhole separate layer injection of polymer solution with single-string. Injecting polymer in 3 layers at the same time, and the drawdown reach 3.6 MPa at the flow rate of 180 m3/d, the rate of shear degradation less than 6%, layered sealing pressure reached to 25 MPa, running and pulling loading smaller than 4 kN. Applications achieved effectively, and control the polymer solution flowing along high permeability reservoir in high speed, improve the development effect of polymer flooding.