A bacterial strain HA-01, isolated from rhizosphere soil, exhibited extensive antagonistic effect on 12 fruit and vegetable pathogens. The strain was identified as Bacillus amyloliquefaciens based on morphological observation, physiological and biochemical characteristics,16S rDNA sequence homology and specific PCR detection. The effects of different treatments of strain HA-01 against disease caused by Penicillium digitatum Sacc. on inoculated mashui mandarin were also investigated. The results showed that the incidence of citrus green mold of mashui mandarin treated by cell culture,cell-free filtrate and cell suspension of strain HA-01 was less than 20% in all treatments while the incidence of control was 94.44%, and the lesion diameter was all below 2.00 cm while the lesion diameter of the control was 3.60 cm.