A high precision closed-loop control positioning system taking the DMC2210 card as a control core is designed, which uses linear encoder as feed-back component to realize the precise positioning of indexing movement. The analysis and optimization pointing to the phenomenon of workbench’s overshoot is carried out in two parts. One part, the relation between stepping motor’s deceleration and ruling precision is analyzed, and then the phenomenon of workbench’s overshoot is optimized preliminarily by the stepwise deceleration’s style. The other part, the influence of spring’s stiffness on workbench’s overshoot problem is analyzed and simulated. After the change for spring with stronger stiffness, the index error caused by workbench’s overshoot phenomenon is improved largely. After the improvements, extensive tests on ruling gratings with density of 79 g/mm are carried out. Experimental results indicate that the precision of the indexing movement at ruling echelle with 79 g/mm is controlled in 5nm.We select one of the better data (the indexing movement’s precision is 2.887 nm) after our improvement to compare with one of the better data (the indexing movement’s precision is 7.759 nm) in the previous tests. The result shows that the ruling engine’s indexing precision is significantly improved.