Based on the survey data of fishery resources collected from 41 stations in June, July, and September 2019 and May, August, and October 2020 in Liaoning offshore, we analyzed the spatiotemporal distribution of the relative biomass and biological characteristics of Hexagrammos otakii and examined its relationship with environmental variables, including water depth, bottom salinity, bottom water temperature, bottom sediment type, month, and year using a generalized additive model (GAM). The results showed that the relative biomass of H. otakii was higher in summer and autumn than that in spring and varied greatly among different survey stations, and the spatial heterogeneity was high. The body length and body weight of H. otakii increased monthly from May to October, and fatness was higher in summer than that in spring and autumn. These biological indexes showed significant differences (P＜0.05) among different months. The spatiotemporal distribution of relative biomass showed that H. otakii preferred two sediment types, namely reef and sandy bottoms, and lower water temperature. The relative biomass of H. otakii in the northern Yellow Sea was higher than that in Liaodong Bay. GAM analysis indicated that water depth, bottom salinity, bottom water temperature, bottom sediment type, month, and year were the best explanatory variables affecting the distribution of the relative biomass of H. otakii. The relative biomass of H. otakii was significantly positively correlated with a water depth of 4.5?55 m, and the relative biomass in Liaoning Ocean was higher with a salinity of 22.9?31.5 and a bottom water temperature of 12?22.5 ℃. The results of GAM analysis were consistent with the ecological habits of H. otakii. Based on the results, we suggested that the northern Yellow sea, which has a wider range of reef and sandy bottoms and lower bottom water temperature, can be used as a suitable area for the stock enhancement of H. otakii and that the months from May to June can be used as a suitable release time when the bottom water temperature rises to 12 ℃ or higher. These suggested areas and times for stock enhancement of H. otakii may better guarantee the survival rate and quality of the released H. otakii population.