The difficulty in casing running needs to be solved urgently for extended reach wells in Bohai Oilfield. Taking a well A in Bohai Oilfield as an example, this paper analyzes the technical difficulties in φ244.5mm casing running from the design point of view, and analyzes the factors affecting casing running using the software of LANDMARK. The results show that if the kick off point becomes shallow, the surface casing running depth becomes deeper, and the hold angle is over large, then less casing unit weight, reduction in the friction coefficient, and increase in the floating section will lead to reduction in casing running friction, and increase in the casing hanging weight. By optimizing the above parameters, the φ244.5mm casing running plan was designed with the floating manner with the length of the floating section as 1200m. The relative error between the predicted value and the measured value of the casing hanging weight was 6.34%, which was within the allowable engineering error range. The casing running design process has been developed for extended reach wells in Bohai Oilfield. In the casing running design, the kick off point, the surface casing running depth, the case weight, the friction coefficient and the floating section should be considered comprehensively to optimize the running plan to ensure successful casing running.