Abstract: A limestone mine is characterized by heavy labor intensity, low production efficiency and poor safety. The medium -length hole blasting technology in pillar and room method was implemented by designing and optimizing open bench blasting parameters. Using orthogonal experiments, three main influential factors of blasting such as the resistance wire, array pitch of hole and stemming length have been optimized. In addition, blast vibration tests were carried out. The relative blast parameters for medium-length hole blasting were ascertained which reduced the ratio of lumpy block, improved the blasting effect and lowered cost of production.