Abstract: BZ34-3/5 oil fields are small marginal oilfield in the Bohai Bay. According to their characteristics, in order to save cost oil produced here was sent to a nearby well-developed oilfields using one simple platform with 2 legs and 3 piles, one seabed pipe, and one seabed cable. Meantime dual electric submersible pump was used here. Daily output reached 300m³, which showed that these two oil fields had been constructed successfully and put into production. It achieved the anticipated goal and significant economic results. Therefore, the development models of small marginal oil field and the application of ESP were briefly introduced in this paper.