Objective To investigate the prevalence of human soil-transmitted nematode infections in Congjiang County, Guizhou Province in 2023, so as to provide insights into soil-transmitted nematodiasis prevention and control in the county. Methods Congjiang County was divided into 5 areas according to geographical locations, and one township was randomly sampled from each area, followed by one administrative village randomly sampled from each township as the survey site. Two hundred permanent residents without deworming during the past three months were randomly sampled from each survey site using the random cluster sampling method. Participants’ fecal samples were collected, soil-transmitted nematode eggs were detected using the KatoKatz technique and the prevalence of human soil-transmitted nematode infections was compared among participants. Mild, moderate and severe soil-transmitted nematode infections were classified according to eggs per gram (EPG), and the proportions of mild, moderate and severe infections were estimated. In addition, participants’ family status and household sanitary toilets construction were investigated using questionnaires. Results A total of 1 001 participants were included at 5 survey sites in Congjiang County, and the overall prevalence of soil-transmitted nematode infections was 19.08% (191/1 001). The prevalence rates of Ascaris lumbricoides and hookworm infections were 2.30% (23/1 001) and 1.90% (19/1 001), with all egg-positives identified as mild infections, and the prevalence of Enterobius vermicularis infections was 0.10% (1/1 001). The prevalence of Trichuris trichiura infections was 15.78% (158/1 001) among participants, and there was a significant difference in the prevalence among survey villages (χ² = 123.345, P < 0.001), with the highest prevalence detected in Liujia Village (39.00%), followed by in Longjiang Village (18.00%). There was an age-specific prevalence rate of T. trichiura infections among participants (χ² = 166.050, P < 0.001), and the highest prevalence was detected among participants at ages of 10 to 19 years (48.19%), followed by at ages of over 70 years (14.53%) and 50 to 59 years (13.04%). There was an occupation-specific prevalence rate of T. trichiura infections among participants (χ² = 74.134, P < 0.001), and the highest prevalence was detected among students (32.32%), followed by among workers/migrant workers (10.34%) and farmers (10.12%). There was an educational level-specific prevalence rate of T. trichiura infections among participants (χ² = 28.761, P < 0.001), and the highest prevalence was detected among participants with an educational level of primary school (21.60%), followed by among illiterate participants (12.03%). There was an ethnicity-specific prevalence rate of T. trichiura infections among participants (χ² = 42.193, P < 0.001). The proportions of mild, moderate and severe T. trichiura infections were 76.58% (121/158), 14.56% (23/158) and 3.16% (5/158), and all severe infections were identified among primary school students. T. trichiura infections were detected in 123 families, and there were 27 families (21.95%) in which two and more family members were identified with T. trichiura infections. A total of 1 001 valid questionnaires were recovered, and the prevalence rates of T. trichiura infections were 14.69% (139/964) and 34.55% (19/55) in families with and without sanitary toilets (χ² = 15.410, P < 0.001). Conclusions The prevalence of soil-transmitted nematode infections was relatively high in Congjiang County, Guizhou Province in 2023, and the T. trichiura infections was notably serious. Intensified soil-transmitted nematodiasis control measures are recommended targeting primary school students, middle-aged and elderly farmers and migrant workers.