We studied the asymptotic behavior of solutions with quadratic growth condition of a class of Lagrangian mean curvature equations F τ (λ(D 2 u)) = f (x) in exterior domain, where f satisfies a given asymptotic behavior at infinity. When f (x) is a constant near infinity, it is not necessary to demand the quadratic growth condition anymore. These results are a kind of exterior Liouville theorem, and can also be regarded as an extension of theorems of Pogorelov [33], Flanders [16] and Yuan [42,43].