The invention discloses a narrow and long type free-form surface part machining track self-adaptive generation method, which comprises the following steps of: constructing a part free-form surface equal-U-height section line set in the length U direction of a part free-form surface, performing lofting through the line set to regenerate a curved surface again, and comparing the deviation of the regenerated curved surface with a given tolerance; when it is judged that the deviation is smaller than the given tolerance, solving the arc length value and the curvature radius minimum value of each section line of the regenerated curved surface, selecting the section cmax with a maximum ratio of the arc length to the line spacing of the regenerated curved surface, calculating a corresponding tangent contact set on the cmax, and conducting point distribution on each section line of the regenerated curved surface through an equal chord height difference method; according to the projection pointset corresponding to the tangent contact set on the maximum section line on the offset curved surface, discretizing each section line on an equal V parameter line to obtain each discrete point set, and further obtaining the machining track of the machining curved surface of the part; according to the invention, the problems of poor adaptability, strong manual intervention, unsmooth planning track,self-intersection and the like of the planning method in the prior art are solved.