Ultraviolet aging of B.mori silk fabric was studied under natural and artificial weathering conditions. Exposed samples were removed periodically and characterized by several analytical techniques. During both types of weathering, the results showed that yellowness index presented a rising trend with the extension of aging time; breaking strength of B.mori silk fabric decreased approximately 93.62%, 43.30% under natural aging 150 days and artificial accelerated aging 80 h, respectively; the peak intensity of amide I, and amide II, etc. significantly declined, even disappeared. At the same time, the conformation transition of B.mori silk was from random coil to β–pleated sheet following the prolonging of ultraviolet aging time. What’s more, the content of amino acid obviously declined especially histidine, tyrosine, and lysine etc. In addition, the results evidenced that during natural and artificial weathering, various performances of B.mori silk fabric changed similarly. So artificial weathering can be used to substitute for natural weathering for its weathering evaluation, which is helpful to understand the aging behavior and take measures to avoid aging and elongate its service life.