Historically, the chub mackerel (Scomber japonicus) has had stable spawning grounds in the offshore water of Yantai-Weihai, China; these spawning grounds have not received considerable attention in recent years. Data on chub mackerel eggs collected from monthly field surveys carried out from April to September in 2020, was used to establish a generalized additive model based on Tweedie distribution (Tweedie-GAM, generalized additive models). This model was used to evaluate the effects of environmental factors on the abundance of chub mackerel eggs. The spatio-temporal pattern of chub mackerel eggs and major habitat factors was plotted to interpret its optimal spawning habitat using the Kriging interpolation method. The distribution and biological characteristics of zero-year-old chub mackerel were also investigated to interpret their early life history parameters. The results indicate that the spawning period of chub mackerel extends from April to July, predominantly concentrated from late May to late June. The main spawning grounds spanned the area between 121°30′?122°15′ E and 37°30′? 38°00′ N. Surface seawater temperature (SST), anchovy (Engraulis japonicus) eggs abundance, ocean current velocity, and surface seawater salinity (SSS) were significant factors affecting the abundance of chub mackerel eggs, with an explained deviance of 54.6%, 17.8%, 4.0%, and 1.7%, respectively. Suitable spawning habitat in the offshore waters of Yantai-Weihai consisted of areas with an SST between 16.3?21.8 ℃, an SSS between 32.1?32.9, and low ocean current velocity, and high anchovy egg abundance. In conclusion, the offshore waters of YantaiWeihai still provide stable spawning grounds for chub mackerel; it is one of the most important spawning grounds for this population in the Yellow and East China seas, and its spatio-temporal distribution is closely related to environmental factors.