Drilling tool falling is a typical downhole accident; it will spend time, manpower and material resources for dealing. The careful drilling tool detection, inspection and good-condition of drilling tool are the main insurance to prevent the accident. However, due to some objective factors, the accident still occurs. The paper presents a typical case of I27H well in Bohai oilfield, drilling tool dropped down to the hole bottom in the drilling process of a 406.4mm well, based on the brief introduction of this well and the accident process, the difficulties of drilling tool fishing in large diameter hole in middle shallow were presented and the feasible fishing scheme was put forward with successful fish operation.