【Background】 As an important part of soil food web, protists play an important role in soil nutrient cycling, and their community composition change can reflect the impact of agricultural management measures on soil ecosystem to a certain extent.【Objective】 To investigate the effects of nitrogen fertilizer combined with straw application on soil protozoa community in Wheat-corn rotation field of North China.【Methods】 In this study, Illumina high-throughput sequencing technology was used to analyze the diversity, composition and structure of soil protist communities under 8 fertilization treatments. The key environmental factors driving the change of soil protist communities were investigated by combining with the determination of soil physical and chemical properties.【Result】 The results showed that straw addition increased soil pH value and the relative abundance of predation protist. In all the treatments, Chlorophyta, Conosa, Cercozoa and Ciliophora were the dominant species, and the relative abundance of Chlorophyta decreased with the increase of nitrogen application concentration. Compared with other treatments, the relative abundance of Apicomplexa was significantly increased in the 300 kg/hm_² (N3) treatments. The protist populations belonging to Cercozoa, Ciliophora and other phyla were mainly predation species, and their proportion increased with the increase of nitrogen application rate in straw returning group.【Conclusion】 Fertilization and straw returning changed soil physical and chemical properties, directly or indirectly affected soil microbial community, and then affected the community of protists. Straw returning increased the Phagotrophs compared with N fertilizer group. This study provided theoretical basis and technical support for the exploration of suitable nitrogen fertilizer dosage under straw returning, and provided reference basis for farmland ecosystem health evaluation and agricultural sustainable development in North China.