Abstract: In order to study the structural change of litchi pericarp infected by Colletotrichum， we used two different pathogenicity of C. gloeosporioides strains， 0977-19-2 with strong pathogenicity and 09619-1-1 with weaker pathogenicity， to infect ‘wuhe’ fruits. The results showed that the structure of pericarp infected by 0977-19-2 changed rapidly， the hypha penetrated the epidermal cells after 1 day， lots of acervulus and conidiums were produced among epidermal cells after 5 days， and acervulus spreaded gradually. The depressed cell of pericarp were dissolved， and none normal cell was existed. The epicarp and palisade tissue treated by 09619-1-1， did not been damaged in 2 days. In the last day， most of cells in sunked pericarp disappeared， and part of spongy tissue cells dissolved. Mycelia and conidiospores were on pericarp. There were significant different responses in pericarp after the infection of different pathogenicity of Colletotrichum. The response on strong pathogenicity was quick， the cells melted rapidly， the speed of invading， colonizing and spreading of strong pathogenicity of Colletotrichum were faster.