The Liuxi River reservoir basin is a typical subtropical mountain basin, and it is of great significance to study the changing characteristics of carbon and nitrogen nutrients concentrations in this basin and its influencing factors to reveal the biogeochemical cycle of subtropical basin. Based on the field sampling of water quality, landscape topography, meteorology, land use as well as soil data, this paper explored the spatial-temporal changing characteristics and the influencing factors of the carbon and nitrogen nutrients concentrations in streams located in the Liuxi River Reservoir basin, using correlation and Elastic Net regression analysis. The results showed that:(1) The temporal trend of carbon and nitrogen nutrients concentrations in streams was relatively stable during dry period, whereas the spatial variation was obvious. (2) The slope of sub-basin was an important environmental factor that caused the changes of carbon and nitrogen nutrients concentrations in different streams, and the slope beyond 6° had a significant positive effect on the change of carbon and nitrogen nutrients concentrations. (3) The average relative humidity of the basin also significantly affected the concentrations of carbon and nitrogen nutrients in streams. The greater the relative humidity of the basin was, the higher the concentration of carbon nutrients in the streams would be, but the concentration of nitrogen nutrients would be relatively low. Compared witth the DOC, the NH₄⁺ and NO₃^- concentrations in streams were less sensitive to the weather conditions. (4) The land use, such as the proportion of the built-up area and other human activities, significantly affected the concentrations of carbon and nitrogen nutrients, as shown by a negative correlation between the built-up area and the DOC concentration. The increased forest cover could enhance the DOC and NO₃^- concentrations in streams, but had no significant effect on the NH₄⁺ concentration. (5) The different soil types also affected the concentrations of carbon and nitrogen nutrients in watersheds, the haplic acrisols had a positive effect on the NO₃^- concentration, and the aric anthrosols had a positive effect on the concentration of NH₄⁺. Overall, our results provide some useful scientific information for the protection of water resources and understanding the changes and influencing factors of carbon and nitrogen nutrients concentrations in the similar watersheds.