Abstract: With the rapid development of science and technology, the tunnel project has received widespread attention. At present, people begin to actively participate in the tunnel excavation project, and in the tunnel excavation link, the most important and main construction tool is the shield machine. The emergence of shield machine has changed the traditional tunneling technology, greatly accelerated the speed of tunneling, and ensured the safety of tunnel engineering projects. As the basic transmission system of shield machine, hydraulic transmission system has the advantages of high precision and large driving force, which makes shield machine become the primary tool of tunnel engineering project. Based on this, this paper analyzes and discusses the hydraulic system of shield machine for reference.