Abstract: The previous studies showed that the hypovirus CHV1-CN280 isolated from North China had higher horizontal transmission abilities than many other CHV1 (Cryphonectria hypovirus 1) stains. In this paper, colonization capability of CHV1- CN280 in field and other biological characteristics were investigated. In comparison in the virulence with the other two well studied hypoviruses, CHV1-CN280 is more close to the mild virus strain CHV1-Euro7 than to the severe virus strain CHV1-EP713. Highly virulent C. parasitica strains became into lower virulent ones after infection with CHV1-CN280. The infected ones were able to colonize chestnut stem tissue and had higher levels of mycelial growth rate and asexual sporulation than strains infected with the prototypic severe hypovirus CHV1-EP713. Preliminary field test showed that CHV1-CN280 had successfully established in the field after inoculation for two years, and furthermore, the hypovirus successfully transmitted into wild virulent strains in the field which were incompatible with the artificially released strains. All the studies suggest that the CHV1-CN280 is of great biocontrol potential in biological control of chestnut blight disease.