In the process of open pit mining,deep hole blasting parameters directly affect the blasting effects(boulder yield and bottom toe) and the blast cost which accounts for a large proportion of the overall cost of open-pit mining.In order to standardize the process of drilling and blasting and to improve the actual production efficiency and economic benefit,optimization tests of deep hole blasting parameters were carried out in Laolongshan limestone mine.In the first stage,blasts were conducted with hole diameter of 90 mm and four different blast hole layout patterns(hole spacing burden) of 4.0 m×3.8 m,4.0 m×4.4 m,4.2 m×4.4 m and 4.5 m×4.4 m.In the second stage,the hole diameter was adjusted to 110 mm,and the hole spacing and burden were increased to 5.0 m×4.8 m and 5.2 m×5.5 m.The crushing hammer is used for secondary crushing of boulders after blasting to meet the requirements of fragmentation.Finally,the most reasonable values of blasting hole spacing and burden were tested according to minimum overall cost of blasting and secondary crushing.By comparing the costs before and after the blast experiments,the optimum hole spacing and burden are 4.0 m and 3.8 m for hole diameter of 90 mm and 5.0 m and 4.8 m for hole diameter of 110 mm.