Trichoderma spp.is a filamentous soil fungus known as an effective biocontrol agent of a range of important airborne and soilborne pathogens,it has universal distribution and economic importance.This article reviewed the researches on biocontrol mech- anism for plant diseases and application of Trichoderma spp.,especially Trichoderma harzianum in recent years. Trichoderma spp., Commonly known as an effective biocontrol agent of a range of important airborne and soilborne pathogens, it has universal distribution and economic importance. This article reviewed the researches on biocontrol mech-anism for plant diseases and application of Trichoderma spp Especially Trichoderma harzianum in recent years.