Aimed at inner wall of pipe,this paper introduces an algorithm of measurement path planning based on spraying robot system.It is premise and basis of model construction and spray. The method of arc length extrapolation and polynomial are simple and prevalent,but they just can meet the need of plant curve which has a finite maximum curvature.Combined with current methods,this paper focuses on pre-scanning measurement method for different cross section curve.The algorithm simulation and model reconstruction test show that this study solves the problem of scanning measurement with collision free for inner wall of airplane intake pipe.