Mixeod-later strucure in the calcium rare-earth fluorocarbonate mineral series has been studied with high resolution electron microscopy(HREM). Five new polytypes, i.e.,B5S2-1H and 3R, B5S4-3R and 6R,B18S10-1H, were discovered in the crystal structure of parisite(BS). For the five new polytypes, the electron diffraction regularity, the crystal structural type and the space symmetry were determined. The complicacy of metallogenic geological environment during the crystallization of new polytypes in the regularr mixedlayer mineral of the type BmSn(m>n) has been revealed by means of the solected area electron diffraction SAED)and HREM.The results show that these regular mixed-layer minerals and new polytypes are usually found coexisting in one natural grain of parisite as the syntactic intergrowth. However, the regular mixed-layer minerals and new polytypes with long-peried ordered stacking sequence are much fewer than those short-period disorder stacking sequence. These new polytypes can be considered as containing layer of bastnaesite(B)and synchisite(S)in the series by ordercd stacking in varying proportions along c axis.