The utility model relates to a secondary layer oil production string for improving the recovery ratio of a secondary layer of an oil reservoir, which can be used for pumping wells with low yield, lowliquid, no water injection wells or small blocks or water injection units with ineffective water injection in the petroleum industry, with many oil layers, large thickness and large interlayer difference, so as to improve the single-well yield of the oil wells. An oil pipe at the bottom of an oil pipe column is sealed, and a throttler and a suction pipe are installed on the lower portion of the oil pipe column. the suction pipe penetrates out of the bottom end of the oil pipe and is inserted into the secondary layer between the production layer I and the production layer II; a suction pipe liquid outlet hole is formed in the suction pipe between the throttler and the bottom end of the oil pipe; a throttler liquid outlet hole is formed in a top plate of the throttler; after output liquid inan oil pipe below the oil well pump or the screw pump is throttled, the output liquid is extracted by the oil well pump or the screw pump, so that the eccentric wear degree of a pipe rod can be effectively reduced, the time of burying an oil layer by sand can be delayed when the oil well pipe is used in a pumping well needing sand-carrying production, the production cost is reduced, and the liquid and oil increasing effects of a secondary layer production well are improved.