The serine protease inhibitors (SPIs) are involved in regulating the balance of endogenous proteins by inhibiting the activities of target proteins and play an important role in plant development and defense mechanisms. In this study, the fulllength ApSPI gene was cloned from Agapanthus praecox ssp. orientalis by using RACE technology. The recombinant E.coli Transetta (pET32aApSPI) was constructed, and the abiotic stress tolerance of the recombinant bacteria was tested. The results showed that: (1) the ApSPI gene was comprised of 652 nucleotides with a 366 bp ORF encoding 122 amino acids. ApSPI was characterized as a Kazaltype serine proteinase inhibitor containing a Nterminal signal peptide and a single putative Kazaltype domain. (2) The optimal induction temperature, duration, and IPTG concentration were 37 ℃, 6 h, and 0.1 mmol·L^-1, respectively. The recombinant ApSPI was mainly expressed in the form of soluble. (3) Analysis of abiotic stress tolerance of the recombinant bacteria showed that the tolerance of recombinant bacteria Transetta (pET32aApSPI) to NaCl (200-400 mmol·L^-1), KCl (200-400 mmol·L^-1) and PEG6000 (5%) was significantly higher than that of the control strain Transetta (pET32a). In summary, overexpression of ApSPI enhanced the resistance of E. coli to salt and drought stress, which laid a foundation for further research on the role of ApSPI in plant stress resistance.