Abstract: Shield machine is one of the main mechanical equipment in the construction of underground tunnel and urban subway. As the core to ensure the normal operation of shield machine, the maintenance of hydraulic system has important economic value and practical significance. Improper maintenance measures will not only affect the working performance and efficiency of shield machine, but also lead to the failure of key components, causing serious equipment damage or property loss, and even threatening the life safety of operators. Based on this, this paper takes the daily maintenance system of shield machine hydraulic system as the breakthrough point, analyzes the common faults and diagnosis methods of shield machine hydraulic system, in order to provide reference for related work.