Mechanization of onion crop lifting is considered of great importance to reduce time, labor and cost that required in the case of hand lifting so, the main objective of the present work was to develop and manufacture a machine to be suitable for harvesting onion crop. The developed harvester is a tractor front mounted. The developed onion- harvester consists of frame, lifting device (blade and collected roller), elevator and collecting device. Experiments were carried out to evaluate the performance of the developed harvester under parameters: four depths of harvest (4- 6- 8 and 10 cm) and four forward speeds (0.720 - 0.837 - 0.947 and 1.125 km/h) under 22%moisture content of to determine field capacity and efficiency, lifting efficiency, total crop losses, power and energy consumed, and total cost requirements for harvesting onion crop. The results indicated that, the maximum field capacity was 0.180 fed/h at speed of 1.125km/h and the maximum field efficiency was 73.9 % at speed of 0.720km/h, it was recorded at depth of 4cm, compared with manual method which recorded the field capacity and field efficiency were 0.125 fed/h and 84.26%, respectively. The maximum lifting efficiency and minimum total losses were 99.2% and 1.9% obtained with the use of the developed onion harvester, compared with manual method which recorded 98.1 % and 2.5%, respectively. The minimum power and energy consumed were 10.112 kW and 59.5 kW.h/fed at depth of 4cm and forward speed of 0.720km/h obtained under onion harvester, compared with manual method which recorded 0.759 kW and 6.072 kW.h/fed, respectively. The criterion cost for manual harvesting was 2400 LE/fed. It was recommended to operate the developed harvester for harvesting onion crop at a depth harvesting of 10 cm and a forward speed of 0.720 km/h where the lowest criterion cost was 674.33 LE/fed, the lowest losses was 1.9%, and the least energy consumed was 59.5 kW.h / fed