At present, when the drilling trajectory is designed, it is usually with the shortest well interval or minimum friction drag / Torque is the design objective. On the basis of the general trajectory design method, the trajectory is adjusted according to the engineering experience of field personnel. However, the existing method has some problems, such as poor applicability of the trajectory engineering to be designed for drilling holes and strong randomness and experience in the design process. Therefore, based on the prediction model of the drilling rate of directional drilling and the prediction and calculation of the build rate of the positive displacement motor, the constraint conditions based on the engineering practice were established, and the general borehole trajectory calculation model was adopted to construct the design method of the borehole trajectory to be drilled with the shortest drilling time as the optimization objective. This method can determine the optimal trajectory design parameters according to the combination profile type, which makes it more applicable, and solves the problems of arbitrariness and high experience of conventional design methods. In addition, this method can orientate to avoid the difficult-to-drill formation, improve composite drilling ratio, improve directional drilling efficiency and shorten drilling cycle. A lateral horizontal well was drilled in the Ordos gas field by using this method. The compound drilling ratio reached 49. 53% , which was 19. 3% higher than the adjacent well, and the friction drag was less than 10T. Under the same geological conditions, the drilling time was saved by about 24h compared with the adjacent well. The well has the potential to accelerate in one run from the sidetrack drilling out point to target A, thus achieving optimal and fast drilling.