An investigation was conducted on the Microtus fortis disaster in the Dongting Lake region of China, aimed to effectively reduce the agricultural production loss caused by this vole. Since 2003, 8 typical sampling sites along the Lake were installed, and the investigation at each site was conducted at least once in each season for more than 3 years. There existed differences in the outbreak risk degree of the M. fortis at different sites, and the East Dongting Lake area was considered as the higher outbreak risk region. The M. fortis population had a singlepeak fluctuation within a year, and peaked in summer. The west bank of East Dongting Lake was the main emigrated area of M. fortis, while the east bank of the Lake was the main immigrated area of this vole, causing the occurrence of M. fortis disaster. There was a close correlation between the quantity and the infection degree of the immigrated M. fortis. Through the analysis on the occurrence patterns of M. fortis disaster at different sites, a corresponding forecast model was established, which could be helpful to the integrative management of M. fortis disaster.