This study investigated the secondary metabolites in the product of rice fermentation with Alternaria alternata and their activity of down-regulating thymosin beta 10(TMSB10) protein expression. The secondary metabolites of A. alternata were separated and purified by various chromatographic separation techniques, including silica gel column chromatography, Sephadex LH-20 column chromatography, and semi-preparative high-performance liquid chromatography. Their structures were identified by spectral techniques such as nuclear magnetic resonance spectroscopy(NMR), infrared spectroscopy(IR), and high-resolution electrospray ionization mass spectrometry(HR-ESI-MS) and comparison with literature data. A total of 10 compounds were isolated and identified, including two new compounds(1S,3S)-2,3-dihydro-3,6-dihydroxy-8-methoxy-1-methylcyclopenta[c][2]benzopyran-5(1H)-one(1), 3,3a, 6-trihydroxy-8-methoxy-1-methyl-2,3,3a, 9b-tetrahydrocyclopenta[c]isochromen-5(1H)-one(2), and the eight known compounds are alternariol 9-methyl ether(3), 1-deoxyrubralactone(4),(3aR)-3,3a-dihydro-1,6-dihydroxy-8-methoxy-3a-methylcyclopenta[c][2]benzopyran-2,5-dione(5), altechromone A(6), alternariol(7), altenuene(8), altenusin(9), and 3'-hydroxyalternariol 5-O-methyl ether(10). The effects of these compounds on TMSB10 expression were tested. Compound 7 showed a significant down-regulation effect on TMSB10 expression with an inhibition rate of 40.5%. The results showed that benzopyrone compounds of A. alternata have the activity of down-regulating the expression of TMSB10 protein, providing theoretical basis and research value for the study of non-small cell lung cancer.