According to many experiments for ANC(Active Noise Control) system, it was found that the order of FIR(Finite Impulse Response) filter and step size of adaptive least mean square (LMS) algorithm will influence the result of noise control. In the present study, it is found that the sampling rate for adopting signals is also an important factor for ANC. A computer simulation for executing ANC in a cylindrical duct was performed in order to explore the relations among these parameters and the sampling rate with the effects of ANC. In this study, it is assumed that the acoustic wave in the cylindrical duct is plannar wave. Also, the interference of the feedback from the second acoustic source, and the delay time for calculation and operation by computer are negligible in the present study. Three effects are discussed from this simulation. First, the relation between the sampling rate and the stability(convergence or divergence) of ANC system is discussed by comparing all the results of the simulation. Secondly, the relation between the step size and the stability of ANC system is discussed while the order of the FIR filter is not changed. Finally, the relation between the order of the FIR filter and the stability of ANC system is explored. The results indicate that the sampling rate should be as high as 100 times of the signal frequency to insure the convergence of the active noise control. purpose of these instructions is to ensure uniformity in the layout and typography of the papers.