Abstract: A modified algorithm of an Active Noise Control system based on Frequency-Selective Filter (FSFANC) is proposed. A FSFANC system selects and deals with one of the components by introducing a Frequency-Selective Filter (FSF) in the signal input channel, and multiple FSFANC systems in parallel can run independently. The proposed algorithm models each module, such as the primary path, the secondary path, the FSF and the control filter, with a simplified Finite Impulse Response (FIR) structure that includes only two coefficients. Theoretical analysis and laboratory experiments show that the system keeps stable even though the frequency of the component biases from that of the FSF by several Hz. The proposed algorithm possesses some advantages, such as simple structure, less computational burden, fast convergence rate, robust stability, and overcomes the limitation of the existing FSFANC algorithm that relied on the strict frequency equivalence of the FSF and the component to be cancelled.