Catalase plays important roles in plant salt tolerance.HcCAT1,a catalase gene from the perennial shrub Halostachys caspica,which distributes in saline-alkali arid land in Xinjiang,was isolated by homologous sequence cloning method.Sequence analysis showed that the ORF of HcCAT1 was 1 479 bp,encodes 492 amino acids with a molecular mass of 56.7 kD and a pI of 6.84.HcCAT1 shared high similarity with those from other plant species.Semi-quantitative PCR results showed that the expression of HcCAT1 gene was up-regulated by salt stress.The recombinant plasmid pET32a-HcCAT1 was constructed and transformed into E.coli BL21(DE3),The fusion protein His-HcCAT1 was expressed by IPTG induction.SDS-PAGE and Western blotting showed that His-HcCAT1 was 77.7 kD,same size to the expected.Under low temperature,His-HcCAT1 was expressed in soluble form,and had certain catalase activity.Salt stress experiments showed that E.coli carrying the recombinant plasmid pET32a-HcCAT1 exhibited better growth phenotypes and higher growth rates than the control bacteria in the LB medium supplemented with 400 mmol/L NaCl,400 mmol/L KCl and 300 mmol/L mannitol,demonstrating that HcCAT1 could enhance the salt stress tolerance for E.coli cells.These results will help to understand the molecular mechanism that H.caspica for salt stress and oxidative stress.