In this study, soil samples were collected from nine representative sites of Cunninghamia lanceolata plantation in Fujian Province, PCR (qPCR) was used to quantify the amoA gene abundances of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), and Clade A of complete ammonia oxidizers (comammox Nitrospira), and the abundance characteristics of ammonia-oxidizing microorganisms and their potential contributions to nitrate in soils were studied. The results showed that Clade A had the highest amoA gene abundance, ranging from 1.32×10⁷ to 1.96×10⁹ copies/g(mean: 3.27×10⁸ copies/g), followed by AOA (9.29×10⁵to 3.23×10⁹ copies/g, mean: 2.94×10⁹ copies/g), and AOB exhibited the lowest amoA gene abundance (2.24×10⁵ to 1.53×10⁹ copies/g, mean: 8.94×10⁶ copies/g). AOA-amoA gene abundance was significantly negatively correlated with soil pH (P<0.001), and positively correlated with C/N ratio, NH₄⁺-N, and available phosphorus(P<0.001), as well as with total nitrogen (P<0.05) and moisture (P<0.01). AOB-amoA gene abundance was only significantly positively correlated with available phosphorus (P<0.001), while Clade A-amoA gene abundance was significantly positively correlated with available phosphorus (P<0.001) and moisture (P<0.05). Random forest and stepwise regression analyses indicated that AOA and soil pH were key factors influencing nitrate nitrogen content, with AOA-amoA gene abundance showing a significant positive correlation with NO- 3-N content (P<0.01). In conclusion, AOA plays a dominant role in the nitrification process in C. lanceolata plantation soils in Fujian Province, and soil pH indirectly regulates nitrate accumulation by affecting AOA activity.