A designing method of supersonic nozzle with controllable contour based on B-Spline curve and characteristic line algorithm is proposed. The contour of the nozzle was adjusted by assigning the distribution of Mach number on the nozzle’s axis. The reliability of the designing method was validated by numerical simulation, which shows that the outflow of the nozzle with high quality can be produced and the contour can be adjusted freely. The result also shows that the nozzle designed by the proposed method can produce better flow than the minimal length nozzle(MLN) with the same length.