From August 2008 to September 2009, the feeding habits of Trichurus lepturus L. in Beibu Gulf of South China Sea were studied by monthly sampling and stomach content analysis. In study area, T. lepturus was euryphagous, which fed on fish, cephalopoda, benthic crustacean, and zooplankton, etc., among which, Bregmaceros rarisquamosu, Decapterus maruadsi, and Acetes chinensis were the main prey components, accounting for 37.99%, 16.42%, and 10.03%, respectively. D. maruadsi and Anchoviella heteroloba appeared throughout the Beibu Gulf all year round, and could be served as the index species for the migration and fishing ground distribution of T. lepturus. The indices feeding intensity and stomach fullness differed significantly among seasons (P < 0.001); while the index prey diversity had no significant seasonal difference (P > 0.05), which peaked in autumn and had an annual average value of 1.97. Cluster analysis revealed that when the preanal length of T. lepturus was 190 mm, i. e., at 50% of maturity length, a clear diet shift happened, from small zooplankton, pelagic fishes, and crustacean for the juveniles to predominantly larger fish and cephalopoda for the adults.