In order to synthesize high value-added β-phenylalanine, the phenylalanine aminomutase was used to convert α-phenylalanine to β-phenylalanine. The phenylalanine aminomutase gene (pam) from Pantoea agglomerans was cloned, the expression vector was constructed for heterologous expression. The results showed that the gene pam with1626 bp encoding 541 amino acids of PaPAM was successfully cloned. The expression vector pET28a-pam was constructed and transferred into E. coli BL21 for induced expression using isopropy-β-D-thiogalactoside (IPTG). The electrophoretically pure recombinant phenylalanine aminomutase (PaPAM) was produced by affinity chromatograph. The product of β-phenylalanine was detected using MS and NMR. The enzyme activity reached 2.5 k U/g under the optimum conditions of 30 ℃, pH 9.0 and 1.5 mol/L NH4+.The enzyme exhibited high stability at 30 ℃～50 ℃ and pH 8～10. Metal ions and surfactants have different effects on enzyme activity. Na+, Mg2+, Ca2+, and Fe3+ have little effect on PaPAM activity, while SDS and Triton 100 can strongly inhibit activity. Under optimal condition, the conversion rate of α-phenylalanine was reached 92 %.