Abstract: Since there are abundant lines feature，plane feature in 3D space，utilizing these information to reconstruct 3D objects has a very broad prospects.However，due to the negative influence of noise and algorithm of extracting straight line，concavo-convex critical edging lines can not be extracted.Thus，how to recognize those not extracted concavo-convex critical edging lines leaves much to be desire.This paper suggests a novel algorithm to resolve this problem by following：Firstly，utilizing matched corresponding lines does space intersection to get space lines.Secondly，utilizing space lines fits space planes by parameter adjustment with constraint.Thirdly，space planes intersect to get concavo-convex critical edging lines.Finally，experimental results prove that our recognition algorithm has correctness，precise and practicality.