The Huguangyan Maar Lake is the biggest maar lake in the world. It is nearly closed and less disturbed by the surroundings. Existing work is mainly on its palaeoclimatological and the ecology environment research. The research on nutrients and their biogeochemical cycling in maar lakes is rare. Therefore, it has great significance to conduct such research in the Huguangyan Maar Lake. Nutrients and related parameters were investigated monthly in the water column of the Huguangyan Maar Lake from October 2015 to September 2016, in order to analyze the compositions, vertical distributions and temporal variations of nutrients and their influencing factors. The results showed that ammonium nitrogen (NH₄⁺-N) was the predominant speciation of dissolved inorganic nitrogen (>60%) in the water of the Huguangyan Maar Lake, followed by nitrate nitrogen (NO₃^--N), and nitrite nitrogen (NO₂^--N) was the lowest speciation. The concentrations of silicate (SiO₃^2--Si) were relatively high, while phosphorus was the limiting nutrient for phytoplankton growth in the Huguangyan Maar Lake. During the winter monsoon, the concentrations of nutrients were vertically stable due to the enhanced vertical mixing. While during the summer monsoon, the water column stratified and nutrients in shallow water were generally low and deep water higher. Monthly variations of NO₃^--N, NH₄⁺-N and SiO₃^2--Si showed obvious variation patterns. Concentrations of NO₃^--N increased from October to March but decreased from March to September; concentrations of NH₄⁺-N decreased from October to May; and concentrations of SiO₃^2--Si decreased from November to May and increased from May to September. Their temporal variations were influenced by combined factors of organic matter decomposition, seasonal water-column mixing, phytoplankton absorption, rain-induced inputs and so on.