Abstract: In this paper, Mikania micrantha leaf spot pathogen was isolated and identified, and the morphology and molecular biology of the pathogen was carried out to determine the suitable growth temperature and host range of the pathogen. The pathogen of Mikania Micrantha leaf spot was identified as Boeremia Exigua., and the optimum temperature for mycelia growth was 27 °C. It was preliminarily found that the pathogen could infect mulberry trees, but not other tested crops.