The invention discloses a blasting method for reducing large rock blocks in a strip mine. The blasting method comprises the following steps of blasting parameter selection, explosive hole forming, explosive filling, water bag filling and blasting. According to the blasting method for reducing the large rock blocks in the strip mine, through reasonable blasting parameter selection, the rock crushing effect is effectively improved, crushing is more sufficient and uniform, explosion gas products can be prevented from rushing out of the hole too early, the flying distance of flying rocks is reduced, safety is improved, the situation that explosives are excessively concentrated at the bottom of the explosive hole is avoided through sectional type charging, therefore, ore rocks at the bottom of the deep hole, in the middle of the step and on the upper portion of the step are blasted to the same degree, the large rock blocks formed due to uneven blasting are reduced, shoveling and transporting are facilitated, the efficiency of open-pit mining is improved, the problem that secondary blasting is needed is solved, the explosive hole is filled with the water bag, the inert rock powder is removed in the explosive hole, and the explosive hole is blocked by the humid loess, so that dust generated by blasting is effectively reduced, the ecological environment is protected, and the method is worthy of popularization.