The topology and working principle of NPC/H-bridge five-level inverter are introduced, and a five-level SVPWM algorithm based on synchronously rotating non-orthogonal coordinate is studied. This algorithm transforms the static Cartesian coordinate to rotary non-orthogonal coordinate which keeps pace with the sector the reference voltage vector located. Sector judgment method is simple; the accurate location of the reference voltage vector can be fast confirmed by using a group formula, and the formulae to calculate the duration of each basic voltage vector is uniform and handy. It can conquer the shortcomings of the traditional five-level SVPWM algorithm, such as, large amount calculation, bad real-time and difficult to apply to higher level. The effectiveness of the algorithm is demonstrated by the experimental results.