This study was conducted to study the biological control of Russian Knapweed (Acroptilon repens L.) by flies head (Urophora xanthippe) in 2010 at Research Laboratory and Greenhouse of College of Agriculture, in Birjand University. This study was due in 2 separate Experiment, the first Experiment The effect of flashed germination of Russian knapweed's seeds and second experiment Performed determine the efficiency of flies head to reduce seed knapweed production. The results showed that use of flies head decreased knapweed germination rate percentage compared to control significantly (P