Abstract: The widely distributed Ethmodiscus rex diatom mat/ooze deposits in the tropical Western Pacific play a crucial role in the global carbon and silicon cycles. However, their precise age and formation mechanism have long been controversial and urgently require reassessment. To clarify the evolutionary history of E. rex diatom mats/oozes in this region, we revisited their chronological framework, evaluates the applicability of different dating methods, and reviewed the currently proposed hypotheses for their formation mechanisms. We systematically compiled previous chronological data for these deposits, including AMS¹⁴C dating data since the Last Glacial period, as well as biostratigraphic and magnetostratigraphic data prior to the Last Glacial period, and combined the latest sediment total organic carbon AMS¹⁴C measurement results from core PD17-36 in the northern West Caroline Basin. The compiled data indicate that E. rex diatom mats/oozes since the Last Glacial period were primarily deposited during the Last Glacial Maximum and the Last Deglaciation, with sporadic distribution in the early Holocene. Deposits prior to the Last Glacial period span a larger timeframe, dating back to as early as the Late Oligocene or Early Miocene, but are mainly concentrated in the Late Pleistocene. Meanwhile, all available dating methods have certain degrees of limitations. The deposition of E. rex diatom mats/oozes in the tropical Western Pacific is not a single geological event but has clear characteristics of multi-stage blooms. To improve the reliability of chronological data, given the widespread scarcity of biogenic carbonates, we recommended to use AMS¹⁴C dating on diatom-bound organic compounds for the samples since the Last Glacial period, and magnetostratigraphic dating for the samples prior to the Last Glacial period. Constrained by the uncertainties in the depositional chronological framework, the available proposed genetic hypotheses, such as “dust-derived silica”, “enhanced stratification”, and “topography-induced deep upwelling” promoting E. rex blooms and subsequent mat/ooze deposition, all face certain challenges.