According to the requirements of variable span and variable depth for the new type variable steel trolley,the hydraulic system was developed by scheme design,theoretical analysis,hydraulic element selection and oil circuit design.The system could meet various operation requirement of the trolley,and combined with the electric control system,the synchronous control of vertical elevating and horizontal stretching for multiple cylinder was solved.Meanwhile,the rapid positioning and accuracy adjustment for formwork system was realized.The research of the hydraulic system can ensure the section quality of cave storage engineering.