Abstract: The biocontrol potential of many fungi against plant-parasitic nematodes has been demonstrated.The objective of this study was to evaluate the toxicity of fungal culture filtrates of 6 Beauveria bassiana strains and 7 accompanying fungi strains to four target nematodes by fermentation filtrate immersion method.Results showed that only B.bassiana Snef2598 strain and its accompanying fungi Snef5 strain were caused more than 80% the corrected mortality of second-stage juveniles (J2) of Meloidogyne incognita and Heterodera glycines after 24 h immersion treatment.The filtrate of all strains had lower activity against Aphelenchoides besseyi,and only one strain of B.bassiana caused more than 40% corrected mortality after 24 h immersion.There were 4 strains of B.bassiana and 5 strains of accompanying fungi which caused the corrected mortality above 90% against J2 of M.incognita after 48 h immersion treatment,and also the same as 3 strains of B.bassiana and one strain of accompany fungi against J2 of H.glycines.The strains had lower activity against A.besseyi,and only 3 isolates of B.bassiana and 2 isolates of accompanying fungi caused more than 60% corrected mortalities after 48 h immersion.Almost all of the strains had higher activity against Caenorhabditis sp. after both of 24 h and 48 h treatment,and the corrected mortality was above 97%.To varying degrees,both the body wall and inside substance of the dead nematode body had been dissolved.In comparison,the two strains B.bassiana Snef2598 and the accompanying fungus Snef5 had high activity against plant parasitic nematode.The potential new bio-control fungal resources for controlling the plant nematode diseases are valuable to be researched furthermore.