Abstract: The new prospected ore-body in the northern area of Xishimen Iron Mine is a gently inclined and fractured thick-medium orebody with serious ground pressure， which is extremely difficult to be mined. The pillarless sublevel caving method is adopted in the mine. With limitation of dip angle and thickness of ore body， the loss and dilution rates are relatively high in the mining. In order to formulate control measures for ore loss and dilution， on the basis of studying the law of ore bulk flow， the law of caving and the occurrence process of loss and dilution， the ore body is divided into different mining areas according to the difference of the number of mining segments in vertical direction. So the measures for controlling ore loss and dilution are formulated respectively. Aiming at the mining area of three sections， the dilution control measures are mainly formulated due to higher dilution. The low dilution ore drawing are controlled by two indicators of the mixing rate of waste rocks and the total discharge amount of single step. For the mining area of smaller than three sections， and once the ore is caved into the goaf， resulting in higher loss rate due to the unconditional recovery of the lower section. Therefore， this loss need to be controlled. The double-way synchronous-distance mining can promote the rapid caving of ore and rock and form the ore-drawing condition of overlying strata to reduce the amount of ore caved into the goaf. In addition， the measures to deal with the problem of retained ore in the ridge during the mining process are summarized. These measures have been applied in the mining process of the new prospected body in the northern area of Xishimen Iron Mine with good effect of the loss rate 16.34% and the dilution rate 22.51%.

Key words: Broken orebody, Thickness-Medium thick orebody, Gently inclined orebody, Sublevel caving mining, Lose and dilution control