To assess the influence of pre-existing mosquito eggs or larvae in aquatic environments on the oviposition site selection of Anopheles sinensis females, oviposition preferences were examined under laboratory conditions using water containing eggs or larvae of varying densities from A. sinensis, Aedes aegypti, or Culex quinquefasciatus. The results showed no significant oviposition preference was observed for water bodies containing different densities of A. sinensis or C. quinquefasciatus eggs. In contrast, a marked preference was detected for water containing A. aegypti eggs at a density of 80 eggs per cup. Additionally, high densities (50 or 100 larvae per cup) of larvae from all three species exhibited a significant attractive effect on A. sinensis females. These results indicate that the presence of mosquito eggs and larvae in aquatic habitats significantly affects oviposition site selection in A. sinensis, with the extent of influence strongly associated with both the density and species of the immature stages present.