Generally, the Temburong formation was observed for both research studies and hydrocarbon exploration. There was few research conducted on its lithostratigraphy and micropaleontological purposes in terms of research studies. However, there is no evidence suggested to observe the paleoenvironment condition of the formation based on the calcareous nannofossils occurrences. Therefore, this research was performed deliberately to identify paleoclimate prediction of Batu Luang, Klias Peninsular based on the assemblages of the calcareous nannofossils. 17 samples have been collected from a measuring section of a cutting hill along the road. Simple smear preparation was used and observed their assemblages were under the light microscope. As many as 27 species have been identified and dominantly preserved by discoasters and sphenolithus. Thus, this formation has been considered an oligotrophic condition and low latitude region due to the distribution of warm-water taxas. Plus, less contribution of cold-water taxa Coccolitus pelagicus to the formation is late Oligocene to early Miocene.