Abstract: Due to the wellbore trajectory changes caused by directional drilling for Well Long 114, the tripping frictional resistance was increased, and it was difficult to draw the BHA out, resulting in the BHA expansion and dropping into the well bottom during back reaming the wellbore. The fish length was 3 205.21 m, and the internal thread swelled and was deformed. Through analyzing the difficulties during accident treatment, the fishing tool was selected and improved . According to the handling program for the accident, the active stuck freeing strength was controlled within the force of thread making position of the fishing tool, and the fish was successfully tripped out finally. The idea and technical treatment can be helpful to the similar type of accident treating.