In this paper, the value of exchange rate was calculated in order to determine comparative advantage in crops of Sari Township during 2009-2010. Hence, first, comparative advantage indices are estimated by using a policy analysis matrix. The results showed that just wheat has a DRC index of one in the minimum amount of national currency exchange rate value. This indicated the fact that only wheat, compared to Rice, Soybean, Canola and Barley in this region, can compete with global markets and had a social profitable production system. Therefore, it is recommended that executive policies, which make competitive ability in wheat, should also be applied for other products.