Abstract: Abralia multihamata is an important cephalopod species in Zhejiang offshore with a high biomass in the continental shelf waters of the East China Sea. It serves as an important bait organism for marine fish. In this study, the biomass of Abralia multihamata was estimated by using the swept area method based on trawl survey data and marine environmental data collected in spring and autumn of 2018 to 2023 in Zhejiang offshore. The relationship between habitat distribution characteristics of Abralia multihamata and environmental factors in spring and autumn was analyzed using generalized additive model (GAM). The results showed that the average biomass of Abralia multihamata in the Zhejiang offshore exhibited notable seasonal variation. It was mainly distributed within the sea area 27°—29°N, 122°—124°E with a depth of 40—70 m. The factors influencing the cephalopod biomass included longitude, latitude, depth, sea surface temperature (SST), sea surface salinity (SSS), and dissolved oxygen concentration (DO). The optimum SST was 14—18℃ in spring and 18—22℃ in autumn. The effect of SSS and DO on the biomass of Abralia multihamata were not significant during the spring season. The optimum SSS was 27‰—35‰ and the optimum DO was found in the range of 7—11 ml/L in autumn. Furthermore, the findings of this study provide a scientific foundation for the conservation of cephalopod resources in Zhejiang offshore, especially in light of the challenges posed by climate change.