Abstract: Taking drag coefficients, lift coefficients and vibration amplitudes in different Reynolds numbers as parameters, the influence of water rivulet on Reynolds number effect and mechanism of vibration caused by such influence were studied through force-measurement and vibration-measurement wind tunnel tests of stay-cable models with water rivulets attached in different positions. The study results show that the water rivulet has a great influence upon changing rules of force coefficients with different Reynolds numbers. The value and changing rule of force coefficients have a very close relationship with vibration. At low water rivulet positions, with the increase of Reynolds number, lift coefficient increases greatly and drag force coefficient decreases greatly, which is similar to critical Reynolds number effect. At the same time, galloping coefficient becomes minus due to the change of force coefficients. The large amplitude vibration under such circumstances can be explained by both the critical Reynolds number effect and galloping. In a high Reynolds number range, lift coefficient changes greatly along with the decrease of a drag coefficient and different amplitude vibrations happen for every water rivulet position. The mechanism of this vibration may be similar to that of the vibration induced by a critical Reynolds number effect.