In this article we report a new and sensitive palaeoclimate proxy indicator-humification degrees of peat. Based on the comparison of humification degrees with other climate proxy records, such as λ13C time series of theC. mulieensis remains cellulose in the same peat profile, we suggest that humification degrees of peat in Qinghai-Xizang Plateau can served as a palaeoclimate proxy indicator. The higher the humification degrees of peat, the warmer-wetter the climate; on the contrary, the lower the humification degrees, the colder-drier the climate. Due to the simple method of determination, humification degree of peat is worthy studying and applying further.