Based on the requirements of VSC-HVDC transmission projects， this paper aims to find out the suitable VSC topology to obtain the best performance of VSC-HVDC， i.e.， relatively optimal VSC topology and related modulation scheme. Firstly， considering relevant measurement indexes， the performances of two-level VSC adopting different modulation schemes are compared. This comparison study balances the contradiction between the harmonic property and switching frequency of two-level VSC. Then， the performances of the relatively optimal topology obtained in this comparison study， two-level 12-pulses， three-level neutral point clamped（NPC） and modular multilevel VSC are also compared. Finally， the conclusion is drawn that two-level VSC based selective harmonic elimination PWM（SHEPWM） and modular multilevel VSC are most feasible， and each has their own application features. In addition， combined with the demands of practical VSC-HVDC engineering construction， the basic methods and experience of equipment type selection are presented and verified by simulations.