Abstract: With the increasing global annual consumption of wheat, it is of great significance to further improve seeds quality and enhance germination and seedling vigor in order to boost wheat yield. Low temperature plasma has been proven to positively affect the germination, growth, and stress resistance of wheat seeds. However, the correlation between the active components in plasma and the treatment effects has not been well characterized. This work aims to establish the quantitative relationship between representative active species and the modification effects, which can guide the selection and regulation of plasma parameters in future applications. Jimai 22 wheat seeds were treated using dielectric barrier discharge (DBD) plasma under different gas environments including He, He/O₂, and He/air. The electrical and optical characteristics were obtained. The results showed that, due to Penning ionization, a higher proportion of He in the environment enhanced the uniformity, stability, and intensity of the discharge. Optical emission spectroscopy revealed five representative active species, including HeI, N₂, N+ 2, H_α, and OI. The H_α line may originate either by the ionization of water migrating from the seeds into the discharge region, or by the detachment of the lipid layer and the exposure of starch granules on the seed surface under the impact of energetic particles. The surface modification effects, physicochemical properties, germination, and growth characteristics of the seeds before and after treatment were compared. Plasma treatment caused cracking and blocky spalling of the seed coat due to the impact of energetic particles. In addition, pit-like damage caused by local overheating at concentrated discharge sites were observed after He/O₂ plasma treatment. Hydrophilicity was improved after plasma treatment, with the water contact angle (WCA) significantly decreasing from about 130° to around 80°. This is attributed to the synergistic effect of reactive oxygen species (ROS), which introduce functional groups on the surface, and the alteration of surface microtopography by energetic particles impact. In terms of germination and growth, plasma treatment significantly increased the germination rate to over 90%. After five days of cultivation, both root length and shoot length of the seedlings showed a slight increase. It is speculated that the enhanced hydrophilicity and the cracks on the seed surface promoted water uptake and stimulated seed activity. However, antioxidant indexes exhibited different trends in different gas environments. He and He/air plasma treatments further enhanced antioxidant activity. In contrast, He/O₂ plasma treatment increased superoxide dismutase (SOD) activity, but the DPPH (2,2-diphenyl-1-picrylhydrazyl) free radical scavenging capacity decreased gradually as the proportion of He decreased. The Pearson correlation coefficient was used to reveal the correlation between the content of active species and the modification effects. The correlation between OI radicals and the modification effects was relatively strong, indicating that ROS played a key role in stimulating seed activity. The germination rate showed a positive correlation with particle concentrations, whereas WCA showed a negative correlation. Besides OI, nitrogen-containing species, represented by excited N₂ and N+ 2 ions, also exerted a certain influence. It is worth noting that HeI and OI affected antioxidant activity to some extent, which is speculated to be due to simultaneous damage to the SOD structure and induction of oxidative stress in seed cells. In conclusion, the two discharge environments with He:air ratios of 8:2 and 7:3achieved the best treatment effects.