Abstract: ERD wells generally have high deviation angle and long stable oblique section, in the drilling process the cuttings are easily accumulated in the well to form the cuttings bed, which leads to the complicated conditions such as the increase of the friction resistance, trip in and out, the underground leakage and even the sticking. Therefore, the well cleaning is one of the key technologies to realize the safety and efficiency of the large displacement wells. The rolling exploration of Weizhou Oilfield in the Western sea area of the South China Sea has been constantly breakthrough, but the marginal oilfields with fault block structure are the main areas in the region, rely on the peripheral production facilities implement ERD wells become an effective way to develop the marginal oil fields. In the light of outstanding problems of well instability and the difficulty of well cleaning in ERD wells in Weizhou oilfield, refer to the eccentric annulus model of power law fluid, increasing the ratio of oil to water, the rheology of strong plugging oil base drilling fluid is reduced, and reducing the consistency coefficient K by 41%, with the optimization of hydraulic and drilling parameters, the turbulent region of eccentric annulus in drilling is increased, cleaning auxiliary tools and other technical measures are adopted to realize the high efficient carrying of drilling fluid and break through the technical bottleneck of the cuttings carrying in ERD well. The application of the above technology solves the technical problem of well hole cleaning in ERD well with high stability angle in Weizhou 11-4N oilfield, improves the effect of carrying rock in the drilling process, reduces the auxiliary cleaning time, and provides experience for the development of the large displacement well in the marginal oilfield.