The existence results of positive ω‐periodic solutions are obtained for the second‐order differential equation with delays −u″ + a(t) = f(t, u(t − τ1), …, u(t − τn)), where a ∈ C(ℝ, (0, ∞)) is a ω‐periodic function, f : ℝ × [0, ∞) n → [0, ∞) is a continuous function, which is ω‐periodic in t, and τ1, τ2, …, τn are positive constants. Our discussion is based on the fixed point index theory in cones.