Aiming at the issues of serious occurrence of potato fungal diseases，mixed occurrence of
various diseases，lacking effective control methods，this paper classified and identified highly effective
antagonistic strain BA-26 screened out at earlier stage，studied the stability of its extracellular metabolites，
and clarified its role on preventing disease and promoting growth．BA-26 strain was identified as Bacillus
amyloliquefaciens，through analyzing morphologic characteristics，physiological and biochemical properties，
and 16S rDNA sequence analysis．This strain showed strong antagonistic effects on 8 potato pathogenic
fungus，and its inhibition ratio against Alternaria solani，Fusarium solani and Fusarium avenaceum was
over 80%．After treating the extracellular metabolites by 100 ℃ for 30 min，UV irradiation for 8 hours，pH
2-10 acid-base，and protease for an hour，its relative antibacterial activities were all maintained above 80%．
Laboratory test of bacteriostatic activity showed that the inhibition ratio of BA-26 filtrate against Fusarium
solani was 91.3%．In pot experiment，the potato root length，fibrous root number，plant height and
chlorophyll content in leaves were significantly increased by 32.07%，111.94%，48.0% and 19.6%，
respectively by applying BA-26 fermentation broth with 20 mL concentration of 4.0×10⁹ cfu·mL^-1 per pot．
The results indicated that B. amyloliquefaciens BA-26 had broad bacteriostasis spectrum，strong stability of
extracellular metabolites，and good disease prevention and growth promotion effect，having great potential for
developing biocontrol agent exclusively for potato．