Results of this study have indicated that not only did B. subtilis strain ABS-S14 and its antibiotics exhibit a strong antagonistic property to P. digitatum growth, but chitosan also greatly inhibited the growth of P. digitatum both in vitro and in vivo. We have discussed the efficiency of B. subtilis ABS-S14, and its crude extract to produce a reasonable disease reduction and enhanced mandarin POX and PAL enzyme levels in response to pathogen attack. The antagonistic ability of bacteria B. subtilis ABS-S14 to prevent fruitdecay was definitely relates to its ability to produce CLPs and to stimulate defense mechanisms in mandarin fruit. Finally, the results from this study have confirmed that B. subtilis ABS-S14,its CLPs and chitosan can control green mold decay of mandarin fruit. Promising topics for further investigation include in vivo antibiotic synthesis of B. subtilis ABS-S14 after application on the pathogen inoculated fruit, and the environmental conditions forthe antagonist microorganism to produce antibiotic CLPs and actas an elicitor of defense related gene expression. These would offerfurther insights into the molecular events of elicitation of plantdisease resistance against pathogen attack.