Abstract: Sulphur commonly abounds in mangrove peats, of which pyrite sulphate and organic sulphur are three dominent kinds of occurence forms and which is characterized with high pyrite sulphur.Authors have studied the genetic mechanism of sulphur in mangrove peats in detail by using such methods as sulphur forms and sulphur isotope analysis and combining them with the space-time variation of sulphur and have drawn the following conclusion: The enrichment of sulphur in peats is intimately relative to peat flat environments and the space-time variation of total sulphur and sulphur forms is under the control of micro-environments still farther; Sulphate in water medium of tidal flats is the final source of sulphur in peats; Sulphur incorporation in peat mainly takes place at penecontemporaneous diagenetic stage and sulphur reducing bacteria play a dominant role during incorporating sulphur processes; performing quantitive depositional environment analysis is the important approach to identify sulphur distribution in ancient sulphur-rich coal fields.