Abstract: Investigation on the interface reactions and matrix alloying of WC_P/Fe-C composites was performed by centrifugal casting a hollow cylinder with composite structure and measuring macrostructures and X ray diffraction analysis and SEM micrography with EDS analysis. In the present work condition, the cylinder, dimensioned by outer diameter 167 mm and inner diameter 87 mm and highness 67 mm, consists of WC_P/Fe-C composites surface layer with 16～20 mm heavy cross section and Fe C alloy matrix core. Results show that the surface of CTC particles was partially dissolved by Fe containing melt,even divided.The fine short stick like crystallites, being WC and W 2C primary phase before eutectic, are in situ separated near to the surface of CTC particles. Far from the CTC particles, some separated, fine particle and web WC, W 2C,Fe 3W 3C Fe 4W 2C,Cr 7C 3 and Fe 3C carbide crystallites, are distributed on the matrix of WC_P/Fe-C composite. Fe C alloy matrix of the hollow composite cylinder is alloyed in different levels, due to the partial dissolve and diffusion of CTC particles.