In the blasting demolition of large-volume reinforced concrete bridges in China, the traditional method of manual drilling of 40 mm small-diameter holes for blasting of bridge pier columns is time-consuming, labor-intensive, difficult to ensure drilling accuracy, and has high construction costs. Based on the experience of previous studies, a new method of large-diameter drilling for bridge demolition has been proposed, which includes technical measures for blast hole diameter, hole layout, powder factor, initiation network, and safety protection. To verify the effectiveness of this new method, the blasting demolition project of Ronghui 2 bridge of Chongqing Lijiatuo compound line bridge south diversion project was selected. According to the structural loading of the bridge and the environmental conditions, delayed initiation technology was used, and explosives were detonated at a certain height above the bridge pier, which led to the bridge sequentially collapsing in place from the center to both ends, achieving the goal of one-time completion of the demolition. In this method, water-mill drilling was used to dig holes into the bridge piers, with a hole diameter of 70 mm and crosswise drilling layout, and nonel millisecond delay detonators were used inside the holes, while electronic detonators were used outside for ignition. Multiple layers of protection were provided by bamboo boards, rubber mats and flexible wire mesh. After ignition, the blasting sound was muffled, and the bridge completely collapsed and disintegrated according to the design requirements, while the impact of flying rocks, blasting vibrations, collapse ground vibrations, and explosion shock waves were all controlled within the allowable range.