Developmental plans of the country emphasize on the exports- focused growth strategy, and export diversification is one of the most appropriate policies in this area. Export diversification moves from primary goods to industrial goods. Yet, export diversification, according to the principles of international trade, must be based on comparative advantage until to change value-added. Changes in the value-added of industrial activities can show manufacturing and export capabilities of a country and also production growth. Due to the importance and high value-added of the agricultural sector in developing countries, added value and influencing factors in triple industries of food, wood, and paper are studied. To this end, human capital and physical capital in agricultural triple industries is considered. The variable of weighted comparative advantage of agricultural triple industries and diversification in these industries are considered for the period of 1998 to 2013 by using panel data. The results of the model estimation indicated that, during the period under study, the wood and paper industries had the lack of comparative advantage in the production and export. This variable will have a negative effect on the growth of valueadded. Exports diversification is only carried out in food industries; however, this variable had a positive impact on the growth of the value-added of agricultural sector industries. The human capital and physical capital have a high positive effect on value-added of the industries in the agricultural sector.