Provided is an on-line crevice corrosion monitoring probe head. Three electrodes are arranged on a probe, and crevices formed by sulfur-free rubber exist among the three electrodes. The size of the crevices is in a range of 0.025-0.1 millimeter. The on-line crevice corrosion monitoring probe head has the advantage of being capable of monitoring the crevice corrosion caused by a corrosion medium to various metal materials. Therefore, device managers can timely know the crevice corrosion caused by the corrosion medium to a device, adopt measures early and prevent accidents before occurring. In addition, the on-line crevice corrosion monitoring probe head is simple in structure, few in investment and easy to produce and popularize.