Agrobacteriurn tumefaciens-mediated transformation(AtMT) method was used to study the genetic transformation in Rhizopus arrhizus of antisense expression vector pBI121-fad2 of VeFAD2 gene.We studied the key factors influencing transformation,such as A.tumefaciens strains,bacterial cell volume initially used,co-cultivation time,effective period and concentration of AS.The results shows that the ideal A.tumefaciens strain is AGL-1,the optimum bacterial cell volume initially used is 50-100 μL and co-culture 24 hours will get the most transformants.At co-culture period,AS induction is indispensable.It is beneficial to improve transformation ratio by adding to 200 μmol·L-1 AS at preincubate period and increasing AS concentration to 400-600 μmol·L-1 at co-culture period.It determined that antisense VeFAD2 gene has been integrated into the genome of R.arrhizus by PCR-Southern detection.