Polymer flooding is an important enhanced oil recovery (EOR) technology, which has achieved significant effects in major oilfields in China. However, long-term polymer flooding has led to increased reservoir permeability difference and polymer plugging. After polymer flooding, a series of development problems such as inefficient circulation of injected media, high injection pressure, and highly dispersed residual oil are commonly encountered in old oilfields. The existing EOR technology cannot effectively use the residual oil in the reservoirs after polymer flooding. Therefore, this paper systematically investigated and analyzed the existing EOR technology in reservoirs after polymer flooding and identified the key technical problems that need to be overcome to further improve the EOR of old oilfields after polymer flooding. The paper proposed that the EOR after polymer flooding can be greatly improved by using the safe and environment-friendly nonoxidizing plugging remover to remove the polymer plugging in the reservoir, adopting “plugging but keeping certain permeability” deep profile control technology to control the flow direction of deep liquid, and subsequently injecting new nano fluid with automatic oil finding and efficient washing functions, which can be a technical direction.