Abstract: Ice accretion on aircraft surface degrades aircraft's aerodynamic performance and results in unpredictable disasters. Large-scale icing wind tunnels are essential for studying the growth process of the ice accretion on aircraft surfaces, the key to which is obtaining the precise ice shape. In the present paper, we developed a laser line scanning imaging-based system for online measuring the three-dimensional geometry of ice accretion in large-scale icing wind tunnels. This system has been successfully demonstrated in tests using an aircraft wing model at China Aerodynamics Research and Development Center's 3 m×2 m icing wind tunnel. Prior to scanning, a tridimensional calibration device was used to acquire all laser plane coefficients, which were later combined with camera calibration parameters to establish a mapping function between image and real-world dimensions. Using a combination of the Steger method and gradient barycenter calculation, we accurately located the laser lines on the intricate ice surface and calculated its three-dimensional coordinates, which were used to reconstruct the entire three-dimensional ice geometry. Experimental results indicate that our measurement system has a repeatability accuracy of 0.18 mm; it can effectively capture the three-dimensional geometry of rime, mixed and clear ice on the airfoil model's leading edge during the growth process. Our results agree well with commercial 3D scanners, with an overall standard deviation of 0.5 mm.