The invention relates to a generalized three-level SVPWM modulation algorithm which is characterized by comprising the following steps: 1) judging a big sector and a small sector in which a reference voltage vector is located; 2) selecting the acting time of vector calculation and resultant vector; and 3) arranging a vector sequence and calculating a duty ratio. The algorithm provided by the invention is mainly used for solving the problem of serious common mode when a modulation ratio of a high-pressure system is small, the common mode voltage of the system is reduced, and smaller THDI can be guaranteed. According to the algorithm provided by the invention, the judgment for the small sector is simplified as two small sectors, procedure codes are optimized, and the vector calculation process is simpler. After the algorithm provided by the invention is adopted, the common mode within a full-voltage modulation degree scope can be improved, the EMI can be effectively reduced, and the smaller THDI can be guaranteed.