Abstract: Lead sheath is commonly integrated into collection submarine array cable structure for offshore wind power, and the sheath is typically externally connected to offshore wind turbines from the outside. The connection section between submarine collector cables and offshore wind turbine was subjected to prolonged stress for a long time, which was easy to lead to cracking damage in the lead sheath, and further lead to insulation breakdown of the main cable. Through analysis of lead sheath cracking cases from the Jiangsu region, root causes of sheath failure were investigated, and impact of sheath cracking on the main insulation was examined, providing reference for lead sheath operation and insulation failure prevention of collecting submarine cable for offshore wind power.