In real-time software, not only computation errors but also timing errors can cause system failures, which eventually result in significant physical damages or threats to human life. To efficiently guarantee the timely execution of expected functions, it is necessary to clearly specify and formally verify timing requirements before performing detailed system design. With the expected benefit of reusability and extensibility, component technology has been gradually applied to developing industrial applications including real-time systems. However, most of component-based approaches applied to real-time systems lack in a systematic and rigorous approach to specifying and verifying timing requirements at an earlier development stage. This paper proposes a component-based approach to specifying and verifying timing requirements for real-time systems in a systematic and compositional manner. We first describe behaviors of the constituent components including timing requirements in UML diagrams, and then translate the UML diagrams into MTER nets, an extension of TER nets, to perform timing analysis in a compositional way. The merit of the proposed approach is that the specification and analysis results can be reused and independently maintained.