The design of horizontal well in dense well pattern or offshore oilfield, the underground obstacles well constraints become more and more difficult. Based on the disturbance well describing the position and shape of, after coordinate transformation, established suitable for the design of dual graph design method to model 3D horizontal well design. The characteristic of this method is that the combined use of vertical profiles and horizontal projection of obstacles, respectively to the interval of the obstacles and the feasible region. This method takes into account the number, shape and location of the obstacle, is a universal method. The method of calculation of 3D horizontal well, good effect of design.