China's foreign exchange reserves, the world's largest, fell $107.9 billion in December to $3.33 trillion, the biggest monthly drop on record, Reuters quoted central bank data as showing on Thursday.
The December figure missed market expectations of $3.40 trillion, according to a Reuters poll.
China's foreign exchange reserves fell $512.66 billion in 2015, the biggest annual drop on record.
The value of its gold reserves stood at $60.19 billion at the end of December, up from $59.52 billion at the end of November, the People's Bank of China said on its website.
Gold reserves stood at 56.66 million fine troy ounces at the end of December, up from 56.05 million at end-November.
China's International Monetary Fund (IMF) reserve position was at $4.55 billion, down from $4.60 billion the previous month. It held $10.28 billion of IMF Special Drawing Rights at the end of last month, compared with $10.18 billion at the end of November.