In order to investigate the electroencephalographic complexity characteristics of shooters under normal, low-light, and noise conditions, Omega complexity is used to examine the spatial characteristics of brain regions during the shooting preparation stage and the differences in brain distribution under different conditions. Electroencephalographic data were collected from 30 shooters under normal, low-light, and noise conditions. Omega complexity was used to quantify the complexity levels of scalp and source-localized signals. The results show that Omega complexity in the anterior brain is significantly higher than that in the posterior brain. This difference is further amplified under stress conditions. Under low-light conditions, scalp electroencephalographic complexity is increased in the right frontal all-band and alpha-band regions. It is also increased in the central theta-band regions and the left parietal theta-band regions. However, scalp complexity is decreased in the left-hemisphere beta-band regions. At the source level, complexity is decreased in the left-hemisphere all-band and beta-band regions. It is also decreased in the anterior brain beta-band regions, the right posterior frontal all-band and beta-band regions, and the right frontal beta-band regions. Under noise conditions, scalp complexity is increased in the central all-band and theta-band regions. However, it is decreased in the middle frontal all-band,? alpha-band, and theta-band regions. Source-level analysis also shows that theta-band complexity in the anterior brain is decreased. It is concluded that the anterior brain plays a dominant role in shooting activities and is associated with advanced cognitive functions. Stress enhances the cognitive load of the anterior brain. Spatial and emotional stress increase right-hemisphere neural network activity. Noise acts as an external stressor and inhibits cognitive functions. Dim lighting acts as a source of sensory deprivation and induces compensatory sensory substitution mechanisms.