The environmental structure of T Tauri star can be understood by its continuum energy distribution. We suggest four evolutionary stages on the base of this environmental change from molecular cloud to the main sequence. A protostar is embedded in a dense envelope which can be attributed to the overall infrared region in continuum spectra. The infalling material from the envelope results in producing a hump in the mid-infrared region. This matter produces a surrounding disk around a central star afterwards. The disk emission changes the spectral index in the overall infrared region. The disk will be developed to a ring structure owing to the formation of planets by its instability and/or the cleaning effect of the inner region of the disk by a central star outflow, contributing to producing a hump in the far-infrared region. The pre-main sequence evolution points of T Tauri stars in H-R diagram strongly support the environmental structure evolution.

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