【Objective】 It is of great significance to explore the distribution of NSC and its components in different organs with seasonal changes for revealing the mechanism of carbon distribution in different age forests. 【Methods】 The contents of NSC and its components in different organs of young and middle-aged Pinus armandii were determined by periodic sampling to explore the seasonal changes of P. armandii during the year. 【Results】 The results showed that, (1) the distribution pattern of NSC and its components in different age forests was basically the same among all organs, with the starch content in roots > leaves > branches > stems. The starch content in stems was significantly lower than that in other organs, while the content of soluble sugar and NSC in leaves, roots and branches was not significantly different. The ratio of sugar to starch in stem was significantly lower than that in other organs. (2) During the whole growing season, NSC and its components were mainly affected by seasons, followed by the interaction between seasons and organs, and the influence of forest age was the least. (3) The correlation between NSC and its components in different forest organs was basically the same, except the negative correlation between young forest ratio of sugar to starch and starch, NSC and middle-aged forest ratio of sugar to starch and starch, the other indexes were positively correlated. 【Conclusion】 In summary, NSC and its component contents in various organs of P. armandii had obvious seasonal fluctuations. When the environment changes, the carbon supply and demand of different organs changed synergistically, which was conducive to the growth of P. armandii, and enhanced its resistance and adaptability to cope with extreme environment.