Objective To investigate the species, population density, habitat, seasonal distribution, and activity rhythm of malaria vectors Anopheles after malaria elimination in Tongren city of Guizhou province in China and the impact of ecological environment change on the distribution of malaria vectors, and to provide a reference for coping with the secondary transmission of imported malaria. Methods In 2017-2020, the all-night light trapping method and the outdoor overnight double-net human-baited trapping methods were used to monitor malaria vectors in Tongren city. The captured Anopheles mosquitoes were classified, identified, and counted based on morphology, and the species composition of malaria vectors and differences in the population density of Anopheles indoors and outdoors and in different habitats were analyzed. Results In 2017-2020, a total of 4 611 malaria vectors were captured by the light trapping method at the surveillance sites of Tongren city, all of which were An. sinensis, and the mean light trapping density was 19.05 mosquitoes/(light·night). Among the investigation sites, livestock sheds had the highest number of 3 322 An. sinensis (72.05%), followed by 978 mosquitoes outdoors (21.21%) and 311 mosquitoes in human rooms (6.74%). Peak activity of An. sinensis in Tongren was observed in July to August, and the activity pattern presented single-peak distribution, with a peak density of 38.84 mosquitoes/(person·night) in late July. The overall nighttime density of An. sinensis first increased and then decreased, with a peak for the activity of An. sinensis at 20:00-21:00 and with the low-frequency period at 02:00-03:00. Conclusion An. sinensis is the only malaria vector monitored in human habitats and surreundings in Tongren city. The population density of An. sinensis is relatively high in livestock sheds, and the outdoor density pattern of An. sinensis is consistent with outdoor activity rhythm of residents at night. There is a potential risk of secondary local transmission caused by imported malaria. Therefore, it is necessary to carry out long-term, continuous, and standardized surveillance of malaria vectors.