In an active noise control system, the effective noise reduction range is greatly affected by the number of channels. The traditional method is to expand the effective noise reduction range (above 3dB) by increasing the number of channels in the system, which has high cost and extremely high demand for computing capability. In order to increase the effective noise reduction range without increasing the number of channels, error sensors and speakers, the relationship of the location of virtual sensor and the effective noise reductions range was investigated in FxLMS dual-channel active noise control system by using a method based on virtual error sensing. The results show that when the virtual sensor is set at different positions, the effective noise reduction range increases in different degrees, from 12cm to 26cm.