Temporal,spectral and spatial characters of 0.3-nm-bandwidth high-energy laser pulse propagating through a long path are studied in detail in one newly constructed beamline of our laser facility.The evolution of propagation,pulse energy and near-field deterioration are analyzed theoretically and experimentally.Substituting argon for air is demonstrated effectively to suppress stimulated rotational Raman scattering and the experimental result provides operating criterion,and engineering parameters for the under-constructed beamlines.