Decapterus maruadsi is a small pelagic fish and is of great significance to the ecosystems in the northern South China Sea. We collected and analyzed the data recorded by the fishing vessels in the western Guangdong waters in winter and summer and remote sensing data including sea surface temperature (SST), chlorophyll a concentration (Chl a) and sea level anomalies (SLA) from 2011 to 2015, using generalized additive model (GAM). Results showed that the catch per unit effort (CPUE) of D. maruadsi in the western Guangdong waters had a significant positive linear correlation with longitude, and the D. maruadsi populations were concentrated in the east of the study area. The total explanation of D. maruadsi CPUE in GAMs was 47.40%, among which, the factors year, month, lunar phase, latitude, Chl a, SLA and water depth explained 9.30%, 13.50%, 6.50%, 1.90%, 1.70%, 4.60%, and 9.90%, respectively. The D. maruadsi populations in the study were concentrated in the area of latitude 21°N, Chl a 0.1-0.5 mg•m -3 , SLA -0.05 m and water depth 80 m. Results of this work will help in understanding the environmental factors affecting D. maruadsi distribution in the western Guangdong waters.