The purpose of this study is to explore the effects of sound elimination in a cylindrical duct by combining a reactive muffler and active noise control (ANC) system. In this system, an FIR filter combined adaptive algorithm of least mean square (LMS) is adopted. The results of control for sound are compared between those before the muffler and after the muffler installed. The results indicate that the sequence of arrangement of muffler can influence the results of active noise control. According to the results of experiment and simulation, the effect of noise reduction in ANC system is influenced extremely by reference signal received. The applicability and optimum position of reference signal are explored to improve the ANC system. The transmission loss and insertion loss in this system are also discussed in detail. Besides, the experimental results indicate that the hybrid system has the advantages over a traditional muffler when the muffler is not designed for the frequency of the noise. Furthermore, the mathematic simulation for acoustic field in a cylindrical duct with a muffler is performed in order to verify the experiment results.