Abstract: Circular arc well section parameter calculation is the most primary question among a series of questions of directional orbit design and actual surveyed trajectory. Due to the complicated calculation formula and trivial deduction course proposed by predecessor, this article derivated a new calculation formula for circular arc well section deviation angle and positional angle based on increment of coordinate identical equation. This series of new formula has advantages of concise symmetry and clear structure. This article also provided a new method of predicting well bottom parameter according to well bore hole curvature, which is invariable of space well circular arc section.