The invention discloses a repair cycle developing method and device for structural components of railway vehicles. The method comprises the following steps: obtaining initial defect sizes of the structural components, wherein the initial defect sizes are obtained based on nondestructive testing of the structural components in the repair process of the structural components; obtaining a theoreticaloperation mileage of the structural components extending from the initial defect sizes to critical defect sizes according to the initial defect sizes, the critical defect sizes and a load spectrum ofthe structural components in a single load history, wherein the critical defect sizes are obtained according to a preset critical defect size determination rule; and determining the repair cycle of the structural components according to the theoretical operation mileage. The device is used for executing the above method. According to the repair cycle developing method and device for structural components of railway vehicles provided by the invention, frequent repair of the structural components is avoided on the basis of ensuring the safety operations of the railway vehicles, and the repair cost is reduced.