Abstract: The diatoms data of core 17940 in the South China Sea in 1994 were analyzed. The results indicate that the proportion of T. nitzschioides var. parva versus T. nitzschioides from the core 17940 is regular. Compared with the existing temperature records, such as δ18O records measured on planktonic Globigerinoides rubber and the sea-surface average temperature in the South China Sea, it shows that the proportion of T. nitzschioides var. parva versus T. nitzschioides from the core 17940 can reflect the changes of the palaeoclimate during the latest pleistocene, i.e. the increasing of proportion indicates the higher temperature, otherwise it means the lower temperature. Thus, the ratio of T. nitzschioides var. parva versus T. nitzschioides can be used as an indictor of palaeoclimate in the South China Sea since the latest pleistocene.