Ammonia-oxidizing microorganisms[ammonia-oxidizing archaea(AOA)and ammonia-oxidizing bacteria(AOB)]are important players in soil nitrification. In this study，the key microorganisms driving soil nitrogen cycling and their main influencing factors in solar greenhouse cucumber were investigated，and the specific distribution of dominant ammoniaoxidizing microorganisms in the root system of cucumber was clarified，in order to provide a research basis for enriching the dominant ammonia-oxidizing microorganisms. In this experiment，high-throughput sequencing was utilized to investigated the correlation between environmental factors and the diversity and community structure of AOA and AOB in the soil of cucumber root system under nitrogen treatment. The results showed that the key ammonia-oxidizing microorganisms were AOB both in cucumber rhizosphere and non-rhizosphere soils from the perspective of diversity. In cucumber rhizosphere soil，the main influencing factor for the abundance and diversity of AOB was pH，and the main inducer for the difference in the community composition of AOA and AOB was the accumulation of NO^3--N，and in cucumber non-rhizosphere soil，the main influencing factor for the abundance and diversity of AOB and the change in the community composition of AOB was NH4+-N. From the perspective of community structure，the key ammonia-oxidizing microorganisms in the cucumber rhizosphere soil were Thaumarchaeota and Nitrosophaera of AOA and Nitrosospira of AOB，and the key ammonia-oxidizing microorganisms in the cucumber non-rhizosphere soil were Nitrosospira of AOB. In cucumber rhizosphere soil，the main influencing factor for Thaumarchaeota and Nitrosophaera of AOA was a decrease in NH4+-N concentration，and that for Nitrosospira of AOB was an increase in NO^3--N concentration； in cucumber non-rhizosphere soil，the main influencing factor for Nitrosospira of AOB was the accumulation of NH4+-N. In summary，AOA and AOB jointly dominated ammonia oxidation in cucumber rhizosphere soil，with the main influencing factors being pH，NH4+-N and NO^3--N. Meanwhile，AOB dominated ammonia oxidation in cucumber non-rhizosphere soil，with the main influencing factors being NH4+-N.