Prokaryotic expression vector of IAA7 protein in Arabidopsis were constructed based on pGEX–KG in this experiment. IPTG was used to induce the expression of IAA7 protein in three Escherichia coli strains, namely, Rosetta, BL21 and Tuner. Fusion protein of GST–IAA7 was isolated and purified through GST SefiroseTM resin, and then the stability of recombination proteins was analyzed in vitro. The results showed that the expression of GST–IAA7 was higher in Rosetta with 0.4 mmol/L IPTG concentration at 25 ℃, and PMSF could significantly prolong the storage time of GST–IAA7 in vitro. Pure protein IAA7 was harvested after GST tag was cut off by thrombin.