The filtered-X least mean square (FxLMS) algorithm is widely used for active noise cancellation (ANC). Some variants of FxLMS algorithms have been studied to reduce computational complexity or to improve convergence rate. In general applications, a long tap length is usually required for the conventional FxLMS method which convergence rate is very slow though its structure is possibly very easy to implement. In this paper, a new ANC system is proposed with a variable tap length and step size FxLMS algorithm. Taking into account the effect of the lowpass filter in the secondary path of an ANC system, the impulse response of the control filter is modeled with a two-sided exponential decay envelope to develop our algorithm. Simulation results show that the proposed algorithm does provide a significant performance improvement on convergence rate and noise reduction ratio compared to the fixed tap FxLMS and previously proposed variable step size FxLMS algorithms.