In this paper, we establish some almost-Schur type inequalities on sub-static manifolds, naturally arising in General Relativity. In particular, our results generalize those in ^[1] of Li-Xia for $r$-th mean curvatures of closed sub-static hypersurfaces in space forms and $k$-scalar curvatures for closed locally conformally flat sub-static manifolds. Moreover, our results also generalize those of Cheng ^[2].