Non-structural carbohydrates (NSC) are the main providers of carbon in plants. Understanding the carbon dynamics of early spring ephemeral plants helps reveal their physiological and ecological adaptation mechanisms to regional environments. This study focused on the common species Gagea nigra in the Yili Valley of Xinjiang, investigating the effects of phenological stages and altitude on bulb NSC and its components (soluble sugars and starch), and analyzing the patterns of NSC metabolic transformation. The results indicate: (1) Across different altitudes, the phenological dynamics of NSC and its components in bulbs are consistent, showing a trend of increasing, then decreasing, and then increasing again. (2) The response of NSC and its components in bulbs to altitude varies with phenological stages; overall, there is a significant negative correlation between bulb NSC and soluble sugar content and altitude (P≤0.05), while the variation in starch content with altitude is not significant (P>0.05). (3) The content of NSC and its components in bulbs is significantly affected by environmental factors (P≤0.05), with soil organic matter, total soil phosphorus, and soil water content being important factors influencing NSC synthesis and metabolism. (4) Although there are fluctuations in the content of soluble sugars compared to starch, the overall metabolic transformation pattern of NSC remains unchanged, with the content of soluble sugars always higher than that of starch. In summary, Gagea nigra has developed a series of physiological adaptation mechanisms to cope with the regional environment. These plants, due to their unique life history characteristics, have established an NSC metabolic transformation pattern dominated by soluble sugars, which does not change in response to phenological or altitudinal variations.