C/SiC composites were prepared by reactive melt infiltration (RMI) of molten Si into the C/C porous preform. Influences of C/C porous preform embedded in silicon powder at different positons on the capillary absorption behaviors were investigated. Lots of free Si can be found inside of C/SiC composites prepared by RMI. The free Si was decreased significantly after desilication treatment of C/SiC composite, the composite density and flexural strength decreased as well.