The invention provides a multi-target voltage optimizing method of a wind power plant cluster. The wind power plant cluster is controlled as a whole, the minimum wind power plant grid-connection point voltage deviation, the minimum wind power plant cluster area transmission loss and the maximum wind power plant cluster voltage stabilization margin serve as the target functions, a wind power plant reactive power adjustable capacity constraint and wind power plant grid-connection point voltage upper and lower limit constraints are taken into account, the voltage optimized value of each wind power plant grid-connection point is obtained through optimizing calculation, and optimal control over the voltage of the wind power plant cluster is realized. The multi-target voltage optimizing method can be integrated in a wind power plant cluster control system and provides support for safe, stable and economical operation of the wind power plant cluster.