In open-pit mining operations, blasting fragmentation quality critically determines mining production efficiency and serves as a key benchmark for evaluating bench blasting performance. This study investigates parameter optimization through field experiments conducted during overburden rock stripping in a deep-hole bench blasting project at an open-pit coal mine, systematically analyzing how blasting parameters influence fragmentation outcomes and ultimately proposing optimized blasting parameters with fragmentation characteristics as the primary evaluation criterion. The results demonstrate that the powder factor has the greatest influence on the average fragmentation size, followed by hole spacing and stemming length. For the blasting uniformity coefficient, stemming length shows the greatest impact, while powder factor and hole spacing have lesser effects. Regarding boulder yield, that powder factor again proves most influential, with hole spacing and stemming length following. Optimal parameter ranges were determined as 0.3~0.33 kg/m3 for that powder factor, 5~5.5 m for hole spacing, and 2.5 m for stemming length.