This paper aims to reveal the distribution pattern of fungal communities of the decomposing fallen logs of dominant species in cold temperate coniferous forest and explore the nutrient-driving factors affecting the distribution of the fungal communities. The Illumina MiSeq high-throughput sequencing technology and R analytical method were used to mine microbial diversity data information, then analyze the diversity and functional differences of fungal communities at the initial stage of fallen logs decomposition of Betula platyphylla Suk., Larix gmelinii (Rupr.) Kuzen, and Pinus sylvestris var. mongolica Litv.. The results showed that Basidiomycota and Trichaptum were the dominant fungal communities for Betula platyphylla Suk. and Pinus sylvestris var. mongolica Litv., and Ascomycota and Acidea were for Larix gmelinii (Rupr.) Kuzen in cold temperate coniferous forest. The diversity analysis showed that the fungal Alpha diversity values from high to low were Larix gmelinii (Rupr.) Kuzen, Betula platyphylla Suk., and Pinus sylvestris var. mongolica Litv.. The difference of tree species has extremely significant changed the Beta diversity of fungal communities on the genus and OTU levels among fallen logs intergroups. The ecological analysis of the fungi showed that saprotroph was the main ecotype of the preponderants. Wood saprotroph was the main lifestyle of the fungi of Betula platyphylla Suk.. and Pinus sylvestris var. mongolica Litv.. Besides, soil saprotroph was the main lifestyle of the fungi of Larix gmelinii (Rupr.) Kuzen. In addition, there were significant differences in pH value, total carbon, total nitrogen, C/N ratio, hemicellulose, and lignin among the three fallen logs. Moisture content, total carbon, total nitrogen, cellulose, and hemicellulose were the main factors affecting the fungal distribution. The enrichment of different tree species to the fungal communities of fallen logs is different, and the microbial diversity and functional changes brought by this difference have the important scientific significance for the material cycle in the cold temperate forest ecosystem.