Abstract: <SPAN lang=EN-US>CaCO</SPAN><SPAN lang=EN-US><SUB>3</SUB>(nano)/SiO</SPAN><SPAN lang=EN-US><SUB>2</SUB> (micron) composite particles were prepared directly by high-energy ball milling.SEM,XRD,TEM,EDS,and FT-IR were used to investigate the phase composition and micro organization of composite particles during the milling process.Particle size,morphology</SPAN><SPAN style="FONT-FAMILY: 宋体; mso-ascii-font-family: "Times New Roman"; mso-hansi-font-family: "Times New Roman"">,</SPAN><SPAN lang=EN-US>and structure of CaCO</SPAN><SPAN lang=EN-US><SUB>3</SUB>/SiO</SPAN><SPAN lang=EN-US><SUB>2</SUB> composite particles were characterized and tested.Results showed that composite particles got refined and well-distributed gradually under a strong impact and pressure along with the milling time increased.Tight ball-shaped CaCO<SPAN lang=EN-US><SUB>3</SUB>/Si</SPAN></SPAN><SPAN lang=EN-US> composite particles were formed after milled 240 min.Nano-sized calcium carbonate particles can be adhered evenly on the surfaces and holes of micron-sized silica particles.During the coating process,there were no new materials formed.Strong mechanical force made the surface crystal structure of nano-sized calcium carbonate distort and the amorphous level of particle surface increase. <FONT face="Times New Roman"><BR></FONT></SPAN>