【Objective】Large-scaled restoration of vegetation in the northern part of the Loess Plateau has promoted development of land-dwelling animals or soil animals in that region by providing abundant food and suitable habitats. Nesting activities of soil animals markedly increase the amount of soil macropores, which in turn significantly affect the transformation, storage and utilization of precipitation. The pores formed by soil animals and plant roots are often tubular and have smooth inner walls good in water stability, and hence significantly contribute to the migration of soil moisture. In recent years, quite a number of studies have been reported investigating macropores formed in the soil by plant roots in the Loess Plateau, but little has dealing with macropores formed by soil animals in the region. Therefore, this study aimed to investigate characteristics of ant nests (Camponotus japonicus) and identify factors controlling their nest structure in the Liudaogou Catchment. 【Method】In this paper, Camponotus japonicus in the Liudaogou Catchment, north of the Loess Plateau was selected as the research object. Subterranean nests of the ants and the native Messor aciculatus were filled with thin mush of orthodontic plaster in the field to produce 3D images of the ant nests for comparison to check their similarities and differences. Besides, a total of 21 iron buckets (20 cm in diameter x 20 cm in height) packed with loam were used to raise worker ants in so as to explore relationship between volume of the nest and number of the worker ants. Moreover, worker ants were introduced into plastic buckets (30 cm diameter x 40 cm height) packed with sand to assess effects of soil moisture content and soil bulk density on structure of the Camponotus japonicus nests. 【Result】The Camponotus japonicus nests in the field stretched out vertically as tunnels and horizontally as a series of planular chambers linked with the tunnels. The nest tunnels ranged from 4.1 to 6.6 mm in diameter and went as deep as 63 cm down into the soil. The cross-sectional area of the planular chambers ranged from 606 to 2 117 mm². The nests had 1 to 3 entrances each. The ant nests in the lab did not vary much in diameter of the tunnel, cross-sectional area of the chamber, and number of the entrances from those in the field. Limited by the volume of the PVC cylinder, the nests went only 30 cm deep, with the channels winding downward without lateral branches developed. Significant differences were observed between the nests of Camponotus japonicus and Messor aciculatus in diameter of the channel, shape and cross-sectional area of the chamber, and depth of the nest. As the ants increased in colony size, the nests gradually increased in size. The Camponotus japonicus community can survive in the soil with moisture content ranging from 60 to 200 g kg^-1. In a proper range of soil moisture, soil texture did not affect much structure of the Camponotus japonicus nests. However, in the sand soils low in moisture content, ant nests were rarely found. Soil bulk density also greatly affected structure of the ant nests, reducing length of the nest, number of the branches, number of the node and total volume of the ant nest when it got heavier. However, tunnel of the nest did not vary much in diameter with soil moisture contents or soil textures. Diameter of the tunnels mainly depends on body size of the ants. 【Conclusion】The research elucidated on a small scale the characteristics of the soil-dwelling ants (Camponotus japonicus) and their affecting factors. All the findings may broaden the scope of the study on soil macropores in the northern part of the Loess Plateau. Such knowledge could in turn be used to develop strategies for enhancing the soil water storage capacity and restoration of sustainable vegetation in the arid region of the Loess Plateau.