At present, Bohai L oilfield has entered the adjustment stage of Cr3+ polymer gel flooding ("polymer flooding"). It is urgent to search for further EOR method after polymer flooding. In view of the actual demand of the oil field, the physical simulation research on the method of improving the recovery rate after the polymer flooding and the optimization of the injection parameters are studied in this paper. The result shows that compared with the" high molecular weight " high concentration polymer solution,the salt resistant polymer solution, "polymer/surfactant" two element system and "alkali/surfactant/polymer" three element system, the increase in recovery rate of Cr3+ polymer gel flooding is larger after polymer flooding, and the technical and economic effect is better. with the increase of the size of the slug injected into the plug, the increase of the recovery rate shows a trend of "first increase and then decrease". When the size of the injected plug is 0.2 PV, the ratio of the largest.Under the conditions of the same size of flooding agent slug, compared with the whole slug, the recovery rate of "Cr3+ polymer gel + water + polymer solution + water" or "Cr3+ polymer gel + water" alternate injection increased greatly, showing that the injection mode can slow down the process of "suction profile inversion" and further improve the wave sum coefficient of low and medium permeability layers.