A specific definition of ship heave movement is given, and an error model of heave measurement is established, based on which a heave filter is designed to realize low-frequency attenuation and quadratic integral of a specific band.Detailed analysis is made to the error characteristics, and the influence of each error source on measurement results is presented. An adaptive algorithm is proposed for estimating the state of wave motion in real time, i.e., the average amplitude and dominant frequency of the wave, based on which the parameter of the filter is obtained to minimize the error.Simulation is made to verify the measurement algorithm.The result shows that:Compared with the traditional digital high-pass filter, the adaptive algorithm performs better in real-time and accurate measurement.