The invention provides an oil field horizontal well under-pressure dragging fracturing modification operation valve and a reverse well-flushing unfreezing method. The oil field horizontal well under-pressure dragging fracturing modification operation valve comprises an upper valve body and a lower valve body which are connected with each other, wherein a main passage and a bridge-type passage are arranged in the lower valve body; one side, facing to the upper valve body, of the main passage is provided with a chamfered ball seat; and a pressure-bearing steel ball is arranged on the chamfered ball seat. According to the technical scheme disclosed by the invention, in a normal fracturing process, fracturing fluid passes through the bridge-type passage in the valve, so that erosion damage is not generated to the main passage and the pressure-bearing steel ball; the reliability of the valve in long-term work is ensured; and the work requirement of more than 3.0m<3>/min of oil tube displacement, thousands of cubic meters of sand and tens of thousands of cubic meters of liquid can be met.