Abstract: <SPAN lang=EN-US style="FONT-SIZE: 10.5pt; FONT-FAMILY: "Times New Roman"; mso-bidi-font-size: 12.0pt; mso-font-kerning: 1.0pt; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA; mso-fareast-font-family: 宋体">Mabian phosphate rock from Sichuan Province was selected as the standard samples and pretreated by sulphric acid.Surface change of phosphate rock particles was studied by scanning electronic microscopy (SEM),energy-dispersive X-ray spectrometer (EDX),and specific surface area (SSA).Results showed that the magnesium element was even distributed on the surface of untreated phosphate rock;there were obviously many pores on the surface of pretreated phosphate rock and the pores may be caused by the decomposition of dolomite and the pretreated phosphate rock was made up of many small inter-connective<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>grains,and magnesium element was not found on the surface of pretreated phosphate rock.Existence of these micropores led to the increase of specific surface area and average pore volume of<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>phosphate rock,and this change would help the increase of decompositon rate of phosphate rock and the filtration improvement of final phosphate slurry.Based on the microcomsic analysis,mathematical models for magnesium removal and phosphorus loss from phosphate rock were set up. </SPAN>