Abstract: Abstract:The biostratigraphy of the Huanglong and Laohudong formations in Zhejiang is less studied, and especially the fusulinid zone is not systematic. So there are some problems about the correct stratigraphic division and correlation. The authors intensively measured the stratigraphic section of the Laohudong Formation and Huanglong Formation in Tonglu, Zhejiang Province, and gathered samples of fusulinids from the section, and by thin section study the authors established two fusulinid zones; they are in ascending order: the Profusulinella simplex zone and Fusulinella bocki-Fusulina mayiensis zone (both belong to the Dalaan Stage). Moreover, the biostratigraphic and lithostratigraphic correlation has been made between this section and the section of the two formations in Changxing, Hangzhou and Changshan in Zhejiang. The correlation results indicate that the Profusulinella simplex zone may extend upward to the middle and lower parts of the Huanglong Formation.