In order to study effects of different levels of nitrogen , Iron and Zinc on qualitative and quantitative characteristics of forage maize (S.C 704 Var.) an experiment has been done in Agriculture research center of Markazi province in Iran in 2002. experimental design was spilt plot in the form of completely randomized block design with 4 replications and 12 treatments. Nitrogen fertilizer at three levels including 150,225 and 300 kgN/ha was the main plot and microelements as sub plot in four levels including control contained the two factors of this experiment( Iron sulfate 4kg/ha , Zinc sulfate 45kg/ha). Results showed that, by increasing nitrogen levels, characteristics as number of leaf per plant, ear length, ear thickness, number of seed per row, number of seed per ear, ear weight, nitrogen percentage, and forage yield was increased significantly. Also characteristics as nitrogen percentage, protein percentage, Zinc scale and Iron scale were influenced by microelements; so that microelement increased above mentioned characteristic significant but in other considering qualities didn't show any significant effects. Changes of Leaf Area Index (LAI) showed that maximum leaf area index during growth season equal 5.7 in maximal amount of nitrogen fertilizer (300 kgN/ha), by receiving 1150 GDD after sowing , also changes of Total Dry Weight (TDW) during growth season was showed that dry weight until received 400 GDD was neutral then increased linearly maximum of gathering of dry weight equal 1754.16 g/cm2 with receiving 1200 GDD 300kgN/ha .