The invention provides a chained static synchronous compensator with an active power adjusting capacity. The chained static synchronous compensator with the active power adjusting capacity comprises three phases of cascading chain links, connection reactors and breakers. Each phase of the cascading chain link comprises n cascading units which are connected in series at the alternating current side. One ends of the three phases of the cascading units are connected to form a neutral point of the static synchronous compensator, and the other ends of the three phases of the cascading units are connected into a three-phase grid through the corresponding connection reactors and the corresponding breakers. The invention further provides a corresponding cascading unit. An STATCOM and a BESS are combined, the capacity of controlling active power and reactive power at the same time is achieved, grid connection of medium voltage and high voltage is achieved in a manner of cascading multiple cascading units, a power switch device which is low in voltage resistance is used for achieving energy conversion of high voltage levels, modularization and redundancy design are easy to achieve, the function of balancing a battery is achieved, meanwhile, a bidirectional DC/DC converter is introduced at the direct current side, and ensuring the cycle life of the battery is facilitated.