Semi-flexible nozzle is a type of flexible nozzle of transonic wind tunnel， which consists of throat block， flexible plate with variable contour and outlet end plate. The semi-flexible nozzle has the advantages of short length， few supporting mechanisms， low construction cost， high system reliability and low operation and maintenance cost， etc. In view of the advantages of semi-flexible nozzle， semi-flexible nozzle is adopted in 0.6 m continuous transonic wind tunnel and 2.4 m continuous transonic wind tunnel of Aerodynamics Research Institute （ARI）of AVIC. Taking the semi-flexible nozzle of the 0.6 m wind tunnel as an example， this paper introduces the design method of the contour of semi-flexible nozzle of ARI of AVIC in detail. The main contents include the design method of the inviscid nozzle contour with continuous curvature， the calculation method of the displacement thickness of the boundary layer with continuous curvature， the iterative design method of the nozzle contour， the design method of the semi-flexible nozzle， and the design method of contour upstream of the throat block. This paper presents a calibration method of nozzle contour，which adjusts the displacement thickness of the boundary layer according to the results of computational fluid dynamics （CFD） and flow field calibration and effectively improves the accuracy of the Mach number at the outlet of the nozzle. The results of flow field calibration of semi-flexible nozzle show that the Mach number deviation in the rhombus region of the semi-flexible nozzle is small， and the flow field uniformity is good， reaching the advanced level of the national military standard.