In order to analyze the large amplitude vibration mechanism of cables based on Reynolds number effect, wind forces measurement and free vibration tests were carried out on cable models with/without artificial water rivulet. In the tests, the cable models without artificial water rivulet were in different surface roughness and those with artificial water rivulet attached were in smooth surface, and artificial water rivulet was attached in different positions respectively. Wind force coefficients, Den Hartog galloping coefficients and free vibration amplitudes were obtained. It is shown that in critical Reynolds number range, there is the possibility that the special wind force coefficient characteristics and flow pattern induce vibration, and this is the possible mechanism for dry cable galloping. The roughness of cable surface can change the intensity of critical Reynolds number effect and the range of critical Reynolds number. The existence of water rivulet can change the critical Reynolds number effect. For some water rivulet positions, in certain Reynolds number range, dCF/dα＜0, vibration happens, which agrees with the Den Hartog galloping criterion. In high Reynolds number range, besides Den Hartog galloping, vibrations are relevant to significant decrease of wind force coefficients and unstable flow pattern.