Sustainability evaluation of irrigated and rainfed agro ecological system study was taken up in the Namakkal district of Tamil Nadu. The net income was higher in sugarcane than the groundnut by 677.45 per cent. The seed, farmyard manure and human labour were significant in both the sugarcane and groundnut farms. Mean technical efficiency of both crops were almost similar. Farm size, Education, income, farmer's participation in village community meeting, frequency of participation in farmer fairs and extension visit had significant positive influence on green technology adoption. Sustainability analyses showed that irrigated agro ecological system was more sustainable as compare to rainfed agro ecological system in the triple front of ecology, economic viability and social acceptability. Livelihood security analyses showed that farmers in irrigated agro ecological system were much secure especially from economic, habitat and social network purview. The goals namely income , nitrogen, phosphorous, potash consumption goal and employment generation goal were achieved in the optimum farm plans.