The recent progress of research on chitinase in plant disease resistance is reviewed in this paper. Purified chitinase from the infected plants inhibits phytopathogen in vitro. The pathogens infection induced the chitinase activity increase and the chitinase isozymes change. The high chitinase activity or specific chitinase isozymes have enhanced disease resistance of plant. The constitutive expression of chitinase genes of the transgenic plant can be effective against pathogens infection. Different chitinase plays a different role in disease resistance of various plants because both various chitinases and phytopathogens are different distribution in infected plant.