Abstract: This study is to select the suitable microcarrier concentration and cell seeding density for enhancing the utilization of microcarrier，and optimize the adhered growth and maintenance of ST（swine Testicle）cells. The effects of microcarrier concentration and seeding density on cell growth and maintenance were investigated using 2 different mediums：DMEM supplemented 10% serum or low serum medium（LSM）. Further，the utilizations of Cytodex 1 microcarrier by ST cells under different conditions were compared. Results were as below：continuous culture of ST cells in T150 flask using LSM lasted for 30 days，and the average specific growth rate was 0.626 d-1，which was 1.15 times of that using DMEM supplemented with 10% FBS. The maximum cell density was 38.3×10 cells/mL and the utilization was up to 58.8% when microcarrier concentration was 3 g/L Cytodex 1 in mixing bottle and seeding density was 10×105 cells/mL. Furthermore，when cultured in perfusion system for 15 days，the final ST cell density reached 36.6×105 cells/mL，which amplified 14.6 times. Conclusively，the uses of serum and microcarrier are favorable for ST cell adhesion and growth to achieve high cell density，but also this increases the cost of introducing microcarrier. Maximum utilization of microcarrier and nutrients in the medium，and the optimal growth and maintenance could be achieved through selecting suitable microcarrier concentration and seeding density. The results in this work provide guidance for further industrial-scale microcarrier culture system producing CSFV vaccine.

Key words: microcarrier, ST cells, classical swine fever virus, cell density