Massive dolostones of the Ordovician Majia}ou Group can be grouped into fine saccharoidal dolostones and coarse saccharoidal dolostones. An analysis of inclusions offers the most direct information for the study of origin of the massive dolostones. Inclusions are poorly developed in the host dolomites of fine asccharoidal dolostones} but are well developed in pore-filling calcite crystals. The homogenization temperatures of these inclusions(24 samples) range from 49℃ to 74℃，and the maximum depth of inclusion formation calculated from such temperatures is 172m. It can thus be inferred that the host dolomites of fine saccharoidal dolostones must have been formed in shallow burial environments with the depth of less than 172m. Inclusions are well developed in the host dolomites of coarse saccharoidal dolostones. Analytical data of Raman Spectra show that these inclusions are commonly methane-bearing ones,suggesting that they must have been formed in deep burial environments. The lowest homogenization temperature of these inclusions is 104℃ (with no pressure correction).and the least depth for inclusion formation corresponding with such a temperature is about 2600m. It is hence believed that the coarse saccharoidal dolostones must have been formed in deep burial environments with hot water dolomitization.