The utility model provides a beam -pumping unit dynamic reactive power compensation device, join data acquisition appearance unit, the electric data acquisition of the ginseng collection unit of dc bus, control signal processing unit and main circuit unit including three -phase electricity, data acquisition appearance unit is joined to three -phase electricity and dc bus electricity ginseng data acquisition collection unit is connected with control signal processing unit, control signal processing unit includes the DSP treater, main circuit unit includes drive circuit who comprises drive module and the three -phase bridge circuit who comprises three two -way insulated gate bipolar transistor, and capacitor bank is connected to three -phase bridge circuit's output, control signal processing unit's output is connected with drive circuit's drive module, main circuit unit output is connected with three -phase grid. The beneficial effects of the utility model are that: the utility model discloses an adopt thyristor -switched capacitor to carry out the undercompensation to realize the dynamic reactive power compensation of surplus through DSP treater control thyristor, finally realize beam -pumping unit reactive power's real time kinematic compensation.