The faults of rotating machineries are generally characterized by the periodic singular impulses. However, the fault features of planetary gearbox are often complex modulated and submerged by other components, for its vibration signal has the characteristics of multi-source and multi transmission path. An informative singular value decomposition (ISVD) filter based on the modulation performance of singular value component signal (SVCS) is developed to enhance the fault characteristics of planetary gearbox and weaken the interference in this paper. The fault features can be detected by the envelope spectrum analysis (ESA). In this method, a fast SVD is firstly performed to decompose the vibration signal into a series of SVCSs. Secondly, the information detector of negentropy combined with cyclic autocorrelation (CA) is applied to estimate the informativeness of each SVCS. Then the ISVD filtered signal can be obtained by the reconstruction of amplified informative SVCSs. Finally, the fault features can be extracted by ESA from the ISVD filtered signal. The performance of the proposed method is verified by simulation study and experimental data measured from a planetary gearbox. Results show that the proposed ISVD-ESA strategy can enhance and extract the weak features of multi-modulation, and it can accurately extract the faults of tooth tip pitting and misalignment of sun gear of the planetary gearbox.