Abstract: Objective To investigate the current status of insecticide resistance and overwintering ecology of Aedes albopictus in Haiyan County, Zhejiang Province, and to provide a theoretical basis for effective control of mosquito population density and scientific prevention of dengue fever outbreaks. MethodsA cross-sectional study was conducted from June to July 2024, Aedes albopictus larvae were randomly collected from five subdistricts (towns) in Haiyan County, and reared to adult mosquitoes in the laboratory. Insecticide resistance was tested using the WHO contact-cylinder method. Concurrently, data on insecticide usage in this area during 2023 was collected. Additionaly, from January to March 2024, water samples from different environments were collected for laboratory incubation, and the incubated adult mosquitoes were identified to species. Results In 2023, 15 kinds of public health insecticides were used in Haiyan County, and 80% of which contained pyrethroids. In 2024, Aedes albopictus showed resistance to 0.40% permethrin, 0.08% beta-cypermethrin, 0.40% beta-cypermethrin, 0.50% malathion, possible resistance to 0.03% deltamethrin, and susceptibility to 2.00% chlorpyrifos and 0.05% propoxur. The overall positive hatching rate of Aedes albopictus was 19.36%, and there was no statistically significant difference among different subdistricts (towns). However, statistically significant differences were observed across different months (12.89% in January, 18.24% in February, 26.39% in March), different habitats (21.94% in urban residential area, 9.79% in rural residential area, 26.96% in parks / scenic spots), different types of water accumulation (11.17% of fixed water accumulation, 8.72% of natural water accumulation, 27.98% of temporary water accumulation, 40.66% of discarded tires), different water quality (9.25% of clear water, 38.05% of turbid water), and the presence of symbionts (2.88% in habitats without symbionts, 21.35% in habitats with symbionts).Conclusion Aedes albopictus has developed significant resistance to commonly used pyrethroid insecticides in Haiyan County. The distribution of overwintering eggs of Aedes albopictus is characterized by site-specific and environmental-dependent. In the future, it is necessary to continuously carry out resistance monitoring to guide the scientific and standardized use of insecticides. Targeted prevention and control of overwintering mosquitoes in early spring (before March), such as the elimination and cleaning of discarded tires and temporary water containers, so as to improve the control efficacy.