Abstract: In this paper, 298 tide gauge stations are used as the research object, and three models of generalized gauss markov (GGM) noise model, autoregressive moving average (ARMA) noise model and Autoregressive fractionally integrated moving average (ARFIMA) noise model are used to estimate the noise model characteristics of the coordinate time series of tide gauge stations and the trend of sea level changes. The influence of time span on the velocity estimation of tide gauge stations analyzed and discussed. The experimental results show that the noise characteristics of coordinate time series of tide gauge stations are mainly ARFIMA(1,0), ARFIMA(2,2), ARMA (1,0); the velocity estimation results of tide gauge stations show that 64.77% of the station velocity values are in the interval of 0 mm/a to 4 mm/a, and the average sea level velocity is 1.25 mm/a, which is on an upward trend. As the time span increases, the velocity uncertainty of the coordinate sequence, of the tide gauge stations, gradually tends to converge from divergence, and a time span more than 110 a helps to obtain a robust estimate of the tide gauge station velocity.