The behavior of phosphorus in the solid state pre-reduction and dephosphorization treatment processes of high phosphorus iron ore by mechanical crushing and screening methods were investigated in the present work. The reduction behavior of high phosphorus iron ore by carbonaceous materials was evaluated as a function of reduction temperature, reduction time and carbon mixing ratio. Most of the phosphorus compounds were not reduced in the low temperature reduction process of high phosphorus iron ore and remained as oxides in the gangue phases. The gangue phase size increased from 5 μm order before pre-reduction up to 20–30 μm after pre-reduction, and most of the phosphorus was still concentrated in the gangue phases even when the degree of sintering and agglomeration of the phases proceeded with increasing the reduction temperature. The dephosphorization treatment of the pre-reduced iron ore by mechanical crushing and screening methods was evaluated as a function of the initial reduction condition, screen size, and the mechanical property of the reduced iron ore phase.