Enzymatic polymerization of 4-aminophenol was conducted using laccase enzyme from Trametes hirsute. The polymerization reaction was carried out in acetate buffer solution ( pH 5.0) at 40℃. After 10h, black solid power was obtained. The molecular weight of the product was determined by MALDI-TOF MS. UV-Vis, FT-IR, DSC and TGA were employed to investigate the structure and thermal behavior of produced poly(4-aminophenol). The possible structure of polymer was speculated. The molecular weight of poly（aminophenol）ranges from 300Da to 1500Da, the degree of polymerization are from 3 to 14. Thermal analysis showed that the decomposition temperature of polymer was 223℃，indicating that the polymer have excellent heat resistance.