Abstract: The water soluble azo initiator—azobis(isobutylamidine hydrochloride)(AIBA) was synthesized using ABIN as material by base catalysis method. The effects of the preparation conditions，such as the concentration of ABIN-methanol solution，sodium methoxide dosage，ammonium chloride dosage，the effect of the first and second step reaction time on the yield of end product was investigated. Thermal decomposition reaction kinetics of AIBA was measured. The chemical structure of azobis(isobutylamidine hydrochloride) was characterized by Flourier-infrared spectra(FTIR) and 1HNMR.Finally，poly(vinyl acetate)(PVAc) was prepared using AIBA as initiator by emulsion polymerization. Meanwhile the relative molar mass of PVAc was tested by Gel Permission Chromatography(GPC). The experimental results indicate that：the thermal decomposition reaction grade of AIBA is 1，the decomposition activity energy is 67.39kJ/mol and the of PVAc reached 4949.