出鐵過程的操作條件包含爐渣體積分率、出鐵仰角、流道機構。當爐渣體積分率從0.2增加至0.3或0.4時，壁面剪應力變化分別增加36.47%與55.42%。在整個出鐵過程，要有效分離鐵水與爐渣且減少鐵水流失，結果顯示鐵水與爐渣之間界面的速度與爐渣黏度扮演重要角色。不同的出鐵仰角從8度至12度會產生衝擊角度與距離均向前位移13%並且在衝擊區的壁面需多承受23.9%磨損。增加鐵水主流道的衝擊區寬度有利於減緩壁面剪應力約15%，同時也降低耐火材使用率。 In order to reduce the coat of refractory and prolong the campaign life of the blast furnace trough has been pursued all the time for iron making. It is well know that is critical to prevent the erosion of the main iron runner. The behavior of hot metal flow in the trough has been considered that the key factor for determining the erosion of refractory in the trough. Based on BF 4 of China Steel Co., Taiwan, providing the geometrical design of main iron trough and operation condition was solved by computational fluid dynamics, discussing about the difference of the laminar flow、k-omega model and solidification model for the action of hot metal flow in the trough and verify that the data of the repair record from the trough. The operation condition during the tapping process includes slag volume fraction, taphole angle, geometrical design of main trough. When the slag volume fraction rises from 0.2 to 0.3 or 0.4, shear stress at the side of the wall increases of 36.47% and 55.42% respectively. Metal-slag separation efficient base on the density difference，the results that the flow velocity at the interface between hot metal and slag, and slag viscosity are the predominant factor. The change of taphole angle from the 8 degree to 12 degree can lead to the displacement of the impingement point of the taphole stream and bubble resurfacing point about 13%, and the side of the wall must bear the erosion of 23.9% at the impingement region in the trough. Increasing the impingement region in the trough is help to lower the shear stress at the wall about 15%, reducing the usage rate of refractory simultaneously.