Abstract: The relationship between rock dip and blasting throwing direction of the layered rock in open-pit mine was explored to optimize the blasting parameters.Taking Huangmailing Open-pit Mine as an example，single-hole blasting crater experiment in field was carried on.Then，the blasting crater profile was drawn by recording large blocks and flying rocks after blasting.Finally，the paper made the orthogonal test of spacing pattern parameters to determine the optimal solution with the application of the Split-desktop software for recording fragment distribution after blasting.The research indicated that the blasting effect is the best when the throwing direction of rock piles is vertical to the rock dip.The best spacing pattern parameters of the ore/explored rock and hard rock is 5.5 m×3.7 m，5 m×3.5 m respectively.The research provides a scientific basis for moderate longhole bench blasting in open-pit mine.

Key words: Open-pit mine, Layered rock, Parameter optimization, Blasting crater, Orthogonal test