For two constants K≥ 1 and K′≥ 0 , suppose that f is a (K, K′) -quasiconformal self-mapping of the unit disk D, which satisfies the following: (1) the inhomogeneous polyharmonic equation Δ nf= Δ (Δ n-1f) = φn in D(φn∈ C(D¯)) , (2) the boundary conditions Δn-1f=φn-1,…,Δ1f=φ1 on T (φj∈ C(T) for j∈ { 1 , … , n- 1 } and T denotes the unit circle), and (3) f(0) = 0 , where n≥ 2 is an integer. The main aim of this paper is to prove that f is Lipschitz continuous, and, further, it is bi-Lipschitz continuous when ‖ φj‖ ∞ are sm...