GDG series shield machine hydraulic cylinder in order to meet the domestic rail transportation, construction of the tunnel shield machine, and other specialized research and development. Shield machine for the high-pressure hydraulic cylinders, eccentric-contained environment and the working condition, using a special seal and the support structure and seal combination of high-strength alloy materials, and reasonable heat treatment process, a comprehensive shield to ensure the performance of hydraulic cylinder and reliability. Has a diameter of 5.64~14.88m series shield hydraulic cylinder, the main focus of the domestic and subway tunnel project has been successfully applied, and quantities of well-known international companies set completely replace imports.