Mechanism of interface reaction and magnetic properties of Fe-TiN system attained by high energy ball milling were studied using Xray diffraction (XRD), Mssbauer spectroscopy and vibrating sample magnetometer(VSM). The results showed that during ball milling, a small amount of Fe atoms diffuse into the interface of TiN grains to form a paramagnetic interface phase TiN(Fe)and the diffusion of Fe atoms saturates with increasing milling time. Meanwhile, Ti and N atoms, as a result of the decomposition of fractional TiN, dissolve into the crystal lattices of Fe to form a ferromagnetic solid solution ofFe (Ti,N). The solid solution of Ti and N atoms make the saturation magnetization of powder samples rise first and then fall with the amount of Ti and N atoms increasing.