The nonlinear elliptic eigenvalue problem − div ( | ∇ u | p − 2 ∇ u ) − div ( | ∇ u | q − 2 ∇ u ) + λ a ( x ) | u | p − 2 u + λ b ( x ) | u | q − 2 u = f ( x , u ) , u ∈ W 1 , p ∩ W 1 , q ( R N ) , where 2 ≤ q ≤ p < N and a ( x ) ∈ L N / p ( R N ) , b ( x ) ∈ L N / q ( R N ) , a ( x ) , b ( x ) > 0 are studied. The key ingredient is a special constrained minimization method.