Abstract: Rice blast disease, caused by heterothallic ascomycete Magnaporthe grisea, is one of the most serious fungal diseases of rice throughout the world. The disease attacks rice plants throughout the season and causes severe yield losses. The pathogenesis of M. grisea is due to a complex process that spans the entire life cycle of the pathogen. The process including germination of conidia, formation of appressoria, differentiation of penetration pegs and proliferation of infectious hyphae is controlled by many genes. The interaction between M. grisea and rice is based on the gene-for-gene hypothesis and the defense responses are often activated by the action of the pathogen avirulence (Avr) gene and the host resistance (R) gene. The studies on molecular biology and genetic mechanism of pathogenicity of M. grisea has occupied pathologists and mycologists for several decades. This paper reviews the research progress related to molecular genetics of pathogenicity of the fungus and its genetic diversity and variation, and summarize research methods of the functional genes.