Valve analysis is a commonly used method to infer high resolution palaeoclimate records from lake sediment, which has been applied to northeastern and southeastern China (). However, limited by appropriate archive, it has not yet been applied to the Tibetan Plateau, which is recognized as an important region for the Eurasian continent and even the global climate evolution. Lake Kusai (approximately 35.62-35.83° N and 92.63-93.25° E) is a closed basin lake situated about 4475 m a.s.l. in the northern part of the Tibetan Plateau. In 2006, a 6-m long sediment core was recovered from the shallow part, which was used for sedimentary and pollen analysis (Liu et al., 2009; Wang et al., 2012). The high sedimentation rate (ca. 1.5 cm/yr) provides us a multi-decadal scale record. However, the sediments show high resolution laminations through the whole core, which was supposed to be annual valve depositions. In 2009, two short cores were collected from the shallow and deep water region, and were used for valve analyses, showing clearly bright and dark layers (Fig. 1). Further comparison with 137Cs and 210Pb dating results confirmed that the sediments in Lake Kusai are annual valves, which may potentially fill in our knowledge gap of valve sediments on the Tibetan Plateau and acquire high resolution climate record.