A heating cargo is solidified by several reasons during carriage. This study is to analyse a cargo accident which 811,202 US barrels of Nile Blend crude oil reamined solid In the tanks after discharge. There are some possibilities that low temperature of Beading cargo below cloud point and wax appearance temperature at loading time, heating interruption during voyage or discharging, and prohibition of crude oil washing during discharging might influence the cargo solidified. But we concluded that the defect of heating system would most affect the heating cargo solidified locally, and which blocked drain hole of bottom transverse and web frame and they obstruct flow of heating cargo in the tanks.