Applying reverse engineering technology to the design of engine port, the reconstruction technology on the free-form surfaces of the engine port were investigated deeply. The data on the 3D surfaces of the engine port sample were collected by means of laser scanner, and the scattered data points were processed in regularization. Triangulation processing of surface data cloud was carried out based on surface grid method. According to the free-form surface technology and curve fitting algorithm used at present, the methods used to reconstruct the port surface were proposed. Taking CATIA software as developing platform, the free-form surfaces of the engine port were reconstructed.