Let f be a non-constant meromorphic function and a = a(z)( ≡ 0, ∞) be a small function of f . Under certain essential conditions, we obtained similar type conclusion of Brück Conjecture, when f and its differential polynomial P [f ] shares a with weight l(≥ 0). Our result improves and generalizes a recent result of Li, Yang and Liu. ′ −a f −a = c, where c is a non-zero constant.Brück himself proved the conjecture for a = 0 and for a = 1, he showed that under the assumption N (r, 0; f ′ ) = S(r, f ) the conjecture was true.