Vienna topology rectifier has the advantages of low switching losses as well as three-level voltage waveform which helps to improve the system power density. A LCL-filter-based three-phase vienna topology rectifier is introduced to further improve the system power density and an analysis is given about the effect of control system digital delay on the system stability under different current feedback. As the vienna topology rectifier can operate on higher switching frequencies compared to traditional three-phase rectifier, a method of designing the LCL filter resonance frequency is presented taking advantages of the DSP digital delay to maintain system stability and reduce the volume of the filter under a certain switching ripple attenuation. The experiments and simulations verify the theoretical derivation and analysis finally.