Low molecular weight AA-SSS copolymer was prepared by the acrylic acid(AA) and styrene sulfonate (SSS) in the existence of (NH4)2s2o8-NaHSO3 system. The best synthesis condition of inhibiting pickling skin swelling was determined by orthogonal test which is n(AA):n(SSS) = 1.5: ,and the dosage of (NH4)2 s2o8 and NaHSO3 is 5% and 3% of the total monomer respectively. Mn of polymer was determined by GPC and which is 2069 and distribution coefficient is 1.05. Pickling with 3％best polymer alone, swelling degree of pickling skin is 11.51％，at the same time, the pickling skin will not swell, if 3.2％sodium chloride (based on limed hides weight) was taken into pickling process, and the usage of salt in the pickling process achieved greatly reduce. Compared with the traditional process, the shrink temperature and physical mechanical properties of wet-blue leather have not obvious changes, the content of chrome in wet-blue leather more uniform, SEM shows that dispersion of section of leather is fine.