The experiments were carried out at El-Maamoria village- El-Gamalia region, Dakhlia Governorate during onion harvesting season 2008-2009 to evaluate onion harvesting crop by a combine machine for harvesting and collecting onion cropandachieving the following factors: Decreasing separation losses, increasing soil pulverization and increasing cleaning efficiency of onion crop. All treatments were carried out on onion crop at two different moisture contents (M₁=24.5% and M₂= 20.5%) and four different of rear angle of ray separator (R₁=0, R₂=5, R₃=10 and R₄=15 degree) with different four vibrator speeds (V₁=170, V₂= 200, V₃=230 and V₄=260 rpm ).The best results of separation losses and cleaning efficiency were at (M₂=20.5%, R₁=5 degree, V₄=230 rpm).