Zhao, X. and Song, X., 2020. Extrapolation algorithm of ship track smoothing based on spline theory. In: Yang, Y.; Mi, C.; Zhao, L., and Lam, S. (eds.), Global Topics and New Trends in Coastal Research: Port, Coastal and Ocean Engineering. Journal of Coastal Research, Special Issue No. 103, pp. 909–912. Coconut Creek (Florida), ISSN 0749-0208.Due to the poor transition effect of traditional ship track control, the shipping pressure is too large. The research on extrapolation algorithm of ship track smoothing based on spline theory is proposed. Based on the principle of spline fitting, a three degree of freedom motion model of ship's horizontal plane is established to analyze the force on the ship in the process of motion, so the motion equation is obtained. The extrapolation algorithm is used to analyze the intersection of wave gates. Considering the actual situation and the influence parameters, the research on extrapolation algorithm of ship track smoothing based on spline theory is completed. The control experiment is designed to compare the track control effect of the proposed algorithm with that of the traditional algorithm. The results show that the combination of the spline theory and the extrapolation method results in a higher fit between the control curve and the actual route, which is obviously superior to the traditional results, and the control effect of the ship track is optimized.