Abstract: In view of the unique reservoir conditions of Bi125 block in Gucheng oilfield, the reservoir engineering method and the numerical simulation technology are used to systematically study the well pattern adjustment technology of conventional heavy oil reservoir, which provides suitable well pattern conditions for the oil displacement system to play the role of oil displacement. The injection parameters were optimized by laboratory experiments and numerical simulation, which effectively played the role of polymer flooding in reducing the fluidity ratio of oil-water, and expanding the sweep volume. The polymer flooding technology of the conventional heavy oil reservoir is applied in Bi125 block of Gucheng oilfield, and the effect of increasing oil and decreasing water is better. It shows good production characteristics from injection capacity, oil well efficiency, amplitude of increasing oil and decreasing water, and realizes the breakthrough of conventional heavy oil chemical flooding technology, which is of great significance for chemical flooding, resource replacement and improving recovery efficiency of conventional heavy oil reservoirs.