In order to achieve good active control effect of fluctuating-frequency and dense-frequency sinusoidal vibration induced by multi-sources which may occur in active-passive vibration isolation devices of marine machineries, the improved algorithm based on multi-channel narrowband Fx-Newton algorithm was studied. The algorithm with adaptive compensator for narrowband filter phase distortion was proposed, which can obtain high robustness for fluctuating-frequency sinusoidal vibration. Next, the multi-reference Fx-Newton algorithm was proposed to control dense-frequency multiple sinusoids in the same narrowband, under the precondition of acquiring multiple independent reference signals from vibration sources. The active control experiments show that the improved narrowband Fx-Newton algorithm can get good control effect on the fluctuating-frequency sinusoidal vibration, and can achieve stable and efficient control on the fluctuating dense-frequency sinusoidal vibration excited by two exciters or two air compressors.