The paper investigates the observer-based H ∞ synchronization for coronary artery time-delay system under the state immeasurement and external uncertainty. A Luenberger-like state observer, the observation system, is designed to realize the state reconstruction of the master system. Based on the Lyapunov stability theory and Lyapunov-Krasovskii functional (LKF), the observer-based synchronization control condition is derived for a coronary artery system subjected to the external uncertainty bounded by L 2 norm. By introducing the delay-interval bounds and delay-derivative limits in LKF, the time-delays are handled by the delay-range-dependent strategy. The tighter upper bound of inequality can be obtained to reduce the conservation by employing further improved result of Jensen inequality and reciprocally convex approach. Furthermore, a decoupling technique is utilized to render the separate and simple controller and observer synthesis condition, which can be further solved by applying the cone complementary linearization approach respectively. Numerical simulations are listed to exhibit the effectiveness of the presented methodology.