Using one strain many compounds (OSMAC) strategy to study the chemical diversity of Penicillium janthinellum F12 collected from a sedimentary environment at a water depth of 35 m in the South China Sea.The compounds were purified by repeated silica gel column,Sephadex LH-20 and reversed medium pressure column chromatography.The structures of compounds were identified by spectroscopic analysis（NMR and MS） as well as comparison with published researches.The anti-phytopathogenic activities were assayed by plate method.A macrolide,brefeldin A (1),was isolated from the liquid fermentation extract of Penicillium janthinellum F12,and four alkaloids,paspalinine (2),13-desoxypaxilline (3),paspaline (4) and verruculogen (5),were isolated from the solid fermentation extract of Penicillium janthinellum F12.At the concentration of 50 μg/mL,compound 1 showed anti-phytopathogenic activities against Colletotrichum gloeosporioides and Alternaria alternata with the inhibition rates at 40.5% and 33.0%.By changing the culture conditions,the silenced genes of Penicillium janthinellum F12 could be activated and different types of secondary metabolites could be produced.