Abstract: A promising biocontrol agent HG28-5，a strain with strong effect on Phytophthora blight of pepper，which selected from the root of healthy wheat（Triticum aestivum Linn.）. In vitro and in vivo experiments were used to determine its antifungal effect and root colonization ability. The results showed that，HG28-5 inhibited mycelial growth，germination of cystospores，and formation of zoospore and zoosporangia of Phytophthora capsici in vitro experiment；HG28-5 performed good control potential against Phytophthora blight of pepper in pot and vinyl house experiment，the control efficiencies were 92.57% and 79.96% respectively；HG28-5 successfully colonized on roots of pepper，the colonized density of HG28-5 was 4.45 × 10⁵ cfu · cm^-1 with Double Layer Filter paper method，in pot experiment，HG28-5 persisted on root of pepper with a relative high population density which was more than 10⁵ cfu · g^-1；Based on the morphological，physiological characteristics and 16S rDNA sequence analysis，the strain HG28-5 was identified as Pseudomonas chlororaphis.

Key words: pepper, Phytophthora blight, biocontrol, biocontrol bacteria, Pseudomonas chlororaphis