FeAl matrix composite was fabricated successfully by hot-pressing. The mechanical properties of FeAl alloys have been widely studies, but their behaviors of surface hardening effect by plasma nitriding has not yet been studied. This study was to analysis the relationship between microstructure of the sintered composite by hot-pressing and surface hardening at plasma nitriding treatment. Surface hardening of FeAl base alloys was improved by plasma nitriding with increasing plasma treatment time. Excellent surface hardness in the FeAl alloys could be obtained by plasma nitriding($ extrm{H}_{ extrm{v}}$ 100gf, diffusion layer: 1100~1450kg/$ extrm{mm}^2$, matrix : 330~360kg/$ extrm{mm}^2$). Diffusion layer size increased with increasing plasma nitriding times and decreased with increasing Sic, content.