Abstract: Fruit Rot Disease was one of the most important disease harming pomelo in recent years. The pathogen was identified as Lasiodiplodia theobromae according to the morphology and sequence analysis of the internal transcribed spacer region of the ribosomal DNA (ITS). The optimum temperature for mycelial growth was 25-30℃. The pathogen could grow under pH 4-11. Fructose and glycine could be used as better carbon and nitrogen sources for growth of L.theobromae, respectively. Urea cannot be effectively used.