Abstract: This paper attempts to analyze the cross-layer capacity from the DSL systems of military field phone line under DMT（Discrete Multi-Tone）.Using the self-similarity of network traffic analysis method appeared in recent years，the characteristic of military field phone line form ADSL communication channel has been researched considering the more NEXT（Near End Cross Talk） interference.At the same time，the overflow probability and the effective channel capacity also have been modeled and simulated by fluid flow model solution.The methodologies have reference value for the furthermore research on communication system of military.