Abstract: The tangential movement of water rivulet has significant effects on the rain-wind induced vibration of stay-cables. For real cables in rain-wind weather, it is likely that water rivulet is non-uniform along cable axis and the phase lag between each part of rivulet movement will be incurred. In this paper, the effect of damping of rivulet movement on cable vibration was investigated, and aerodynamic derivatives were obtained by means of wind tunnel tests. Water rivulet models were simplified as one segment of straight line for uniform case, and two segments for non-uniform case. For uniform case, water rivulet movement tends to stabilize or destabilize cable vibration, depending on the phase lag between water rivulet movement and cable vibration. For non-uniform case, the phase lag between the two water rivulet movements has significant effect on cable vibration, the smaller the phase lag, the stronger the cable vibration. When phase lag approaching 180°, the two rivulet movements tend to cancel out each other, and their effect will depend upon the central position of movement range.