Arbuscular mycorrhizal fungi (AMF) are important beneficial fungi that colonize plant roots through soil and mutually coexist with host plants. Exploring the changes in soil nutrients and mycorrhizal colonization status of Chinese fir forests of different ages could be benefit for in-depth understanding of the interactions between nutrients and mycorrhizal fungi in fir forest, providing suggestions for the improvement of soil fertility and promoting sustainable management of Chinese fir forest. In this study, 10-year-old (10a), 25-year-old (25a), and 45-year-old (45a) pure Chinese fir forests were selected, and the relationships between mycorrhizal colonization rate, spore density and rhizosphere soil nutrients (total phosphorus, available phosphorus, total potassium, and available potassium) were analyzed. The results showed that:(1) Both mycorrhizal colonization rate and spore density increased with forest age, while pH decreased with forest age. (2) The content of phosphorus in the rhizosphere soil is low. With the effects of soil acidification and arbuscular mycorrhizal fungal accumulation, rhizosphere phosphorus exhibited a trend of U shape. (3) Although the content of available potassium did not change with stand age significantly, the arbuscular mycorrhizal fungi promoted the accumulation of potassium in the rhizosphere soil. Therefore, arbuscular mycorrhizal fungi can effectively regulate the nutrient dynamics of rhizosphere soil and slow down the nutrient loss caused by soil acidification.