In this paper, we present some inequalities for sector matrices with negative power. Among other results, we prove that if A,B ∈Mn(C) with W(A),W(B) ⊆ Sα, then for any positive unital linear map Φ, it holds <((1 − v)Φ(A) + vΦ(B))r ≤ cos2r(α)<Φ((1 − v)Ar + vBr), where v ∈ [0, 1] and r ∈ [−1, 0]. This improves Tan and Xie’s Theorem 2.4 in [22] if setting Φ(X) = X for every X ∈Mn(C) and replacing A by A−1, B by B−1, respectively, and r = −1, which is also a special result of Bedrani, Kittaneh and Sababheh’s Theorem 4.1 in [4]