Camellia oleifera is an important woody oil crop in southern China. Due to its generally weak disease resistance, it is susceptible to various diseases, among which southern stem blight is one of the major threats to its production. This study systematically screened and analyzed the non-volatile metabolites produced by Trichoderma semiorbis FJ059 with antagonistic activity against Sclerotium rolfsii, the causal agent of southern blight in C. oleifera, and identified the potential antifungal components. The antagonistic effects of non-volatile metabolites produced in different solid-state fermentation media were compared using the growth rate method of mycelia. Results indicated that rice was the optimal substrate, yielding the highest antagonistic effect (99.61%). The solid-state fermentation products in rice media were extracted using different solvents. The ethyl acetate extract exhibited significantly higher inhibition activity than the aqueous extract. When the concentration was 500 μg/mL, the inhibition rates was 98.84% and 44.18%, respectively, indicating that the solvent selection play a vital role in the extraction of active compounds. LC-MS analysis identified several key active substances in the ethyl acetate extract, including nootkatone, caryophyllene oxide, farnesol, pyrrole-2-carboxylic acid, and trans-ferulic acid, all of which demonstrated significant antagonistic effects against S. rolfsii. Notably, the inhibition rate of 200 μg/mL nootkatone and 300 μg/mL caryophyllene oxide were both 100%, while 400 μg/mL farnesol, 400 μg/mL pyrrole-2-carboxylic acid, and 400 μg/mL trans-ferulic acid were 78.30%, 69.38% and 69.77%, respectively. The results indicated that medium-polarity or hydrophobic small molecules in the solid-state fermentation products of T. semiorbis FJ059 were potential antifungal components. The results indicated that the medium-polarity or hydrophobic small molecules detected in the ethyl acetate extract of solid-state fermented T. semiorbis FJ059 were closely associated with antifungal activity, suggesting that the ethyl acetate extract may enrich certain compounds with antifungal potential. The findings would provide new theoretical support and bioactive compound resources for the development of novel and efficient biocontrol agents against southern blight in C. oleifera.