Abstract: Using maize inbred lines 178 and R18hong immature callus as receptor materials, hygromycin sensitivity experiments to confirm the suitable selection pressure ( hygromycin was 15 mg/L ~25 mg/L)were conducted. RNA interference expression vector of starch branch enzyme gene was transformed into maize inbred lines by Agrobacterium tumefaciens and the conditions of Agrobacterium tumefaciens system were studied .The results showed that the inclusion of acetosyringone (100 μmol/L) and ascorbatic acid (50 mg/L) in both infection medium and co-cultivation medium, LBA4404 concentration of fermenting liquor was OD600 0.6 and infection time was 20 min were optimal transformation system. The differentiated transformed callus was examined by PCR, which indicated that the genes had been transferred into genome of maize successfully, transformation ratio reached 2.4 %.