[Objective] To explore the effects of bio-control and growth-promoting of the siderophore involved with Ser gene in Act12, the siderophore synthase Ser gene knock-out mutant was generated. [Methods] For generating deletion mutant, suicide plasmid pKC1132 was chosen as a basic vector, kanamycin resistance gene as a marker, upstream and downstream of Ser gene as homology arms to construct the recombinant plasmid named pCT12. Then, it was transfered into Act12 by conjugal transfer. Putative deletion mutants were verified by PCR. Whereafter, biological analysis was conducted to assess the role of Ser gene in bio-control and growth promoting. [Results] The Ser deletion mutant ?ser was obtained by PCR and sequencing. Results of biological analysis showed that ?ser synthesizes less siderophores compared to wild strain Act12. Furthermore, the seed germination rate of Cucumis melo L and the antagonism against Macrophoma kawatsukai both significant declined. [Conclusion] These results suggest that Ser gene of Act12 has a certain impact on bio-control and growth promoting, which would establish the foundation for further mechanism study.