Abstract: The Hydroponic System (HS) has obtained the soilless technology can produce more than 10 crops of leafy vegetable with rapid growth, high yield and superior quality. The aim of this study is to identify and monitor the hydroponic "Green Oak" lettuce growth development and yield under LED supplement and to evaluate the start-up cost and energy consumption of the hydroponic system with LED light. The NFT-hydroponic and commercial nutrient solution under high plant’s density condition and three difference of LED array was applied. Plant yield and energy consumption were evaluated by the method of Poulet and Barbosa. The results show that the hydroponic "Green-Oak" lettuce under LED R70+B30 indicated the highest yield. The start-up cost of HS-LED is about 220 USD/m². The energy per unit of total biomass is 0.038 kWh/g and the power density of the proposed LED lighting in average is 0.22 kW/m². It is possible to apply LED lighting for hydroponic greenhouse in the high plant’s density which could produce a high yield and a good quality of the lettuce. The LED light array consumed the largest number of energy, for energy sustainability, the LED needs to be switched to low power consumption types and a new design for the LED light source should be applied. The results from this study could be applied to design for the effective of HS-LED in the next step.