Before analysis with GC-MS, deconjugation of estrogen conjugates with acid-catalyzed solvolysis or enzymatic hydrolysis is regarded as the indispensable procedure. However, in our study we found in the first time that estrogen sulfates (Estrone-3-sulfate, E1-3S; Estradiol-3-sulfate, E2-3S; Estriol-3-sulfate, E3-3S) could be directly analyzed with GC-MS, and the deconjugation procedure can be omitted. In the procedure, estrogen sulfates could be directly derivatized to their corresponding free estrogen derivatives, in which mixture solution of N, O-bis-(trimethylsilyl) trifluoroacetamide (BSTFA) plus 1% trimethylchlorosilane (TMCS) was used as the derivatization reagent, and the derivatization conditions were determined at $80^{circ}C$ for 90 min. Possible mechanism of the direct derivatization of estrogen sulfates by BSTFA plus 1% TMCS was suggested. This finding indicated a latent favorable analytical method of estrogen sulfates for environmental samples.