Abstract: In order to improve the efficiency of dragline operation，statistical study has been made on time consuming of dragline single-operation cycle in Heidaigou surface mine. The results have shown that mining methods and geometry of soil bench are the main influence factors of digging efficiency and put forward combined-type digging and changed partial geometry shape of soil in order to improve digging efficiency. Time consuming of equipment rotation is the main factor that influence the efficiency of single operation cycle, so rotation angle ratio of acceleration and deceleration process should be 3/2 in rotating and 4/5 in returning step respectively. Time consuming of bucket ascension is the key factor which restricts the efficiency of coal trench excavation. Reference table of dragline operation has been made according to the restrictive relation between bucket ascension and equipment rotation.

Key words: dragline, overcast stripping, circulating time, operational efficiency