The objective of the present study was to evaluate and tested the performance of the modified potato harvesting device. The effect of some engineering factors such as speed ratio (l)of 2.31, 2.89, 3.59 and 4.48 and eccentric radiuses of crankshaft (r) of 15, 25, 35 ands 45 mm were studied. Results indicated that the speed ratio (l) of 3.549 gave the best values of fuel consumption and specific energy requirements. The results also showed that the eccentric radiuses of crankshaft (r) ranging from 15 to 25 mm gave the minimum values of fuel consumption and   specific energy requirements. The speed ratio (l)of 3.59 and eccentric radiuses of crankshaft (r) ranging from 25 to 35 mm are considered the proper results of the lifted, undamaged and damage tubers percentages. Also, the results revealed that the modified machine reduced the operation cost of harvesting potato tubers per fed. by 26.88% when compared with the use of traditional system (Chisel plow).