The microst ructural features of clacium-rare earth (Ca-RE) fluorocarbonate minerals f rom Southwest China were studied by using selected area elect ron diff raction (SAED) and high resolution transmission elect ron microscopy (HRTEM). Three new regularly mixed2layer st ruc-tures of B8S6 type with long period and different stacking sequence, i.e.B8S62 Ⅰ, B8S62 Ⅱ, andB8S6 2Ⅲ, were found in the derived polycrystal of parisite, in which their st ructural symmet ry, cell parameters, chemical formulas of crystal and stacking models of st ructural unit layer, etc. were determined. The result s of this study also show that these new regularly mixed2layer st ruc-t rues were formed by order stacking unit layer of bastnaesite (B) and synchisite (S) in varying pro-portion along c axis. The observation under HRTEM reveals that in the three new regularly mixed-layer st ructures there are different dist ribution modes of Ce2F ion layers, CO2-3 ion groups between the Ce2F ion layers, and CO2-3ion groups between Ce2F and Ca2+ion layers, and there are some heterogeneous textures, such as disorder interlayer and stacking fault. It further proves the complexity of the crystal st ructure of the Ca2RE fluorocarbonate minerals.