Hydraulic balancer of beam-pumping unit

The utility model discloses a hydraulic balancer of a beam-pumping unit. The hydraulic balancer of the beam-pumping unit comprises balancing weights located on a balance beam. The balancing weights are composed of the quantitative balancing weight and the variable balancing weight. The variable balancing weight is a balance weight water tank fixedly arranged at the tail end of the balance beam. The balance weight water tank is provided with a water inlet pipeline, a water outlet pipeline and a vent hole. The water outlet pipeline is connected with a water pump station. The water pump station is sequentially composed of a water tank, a first two-position three-way valve, a water pump, a one-way valve and a second two-position three-way valve according to a water path. When water is supplied to the water tank through the second two-position three-way valve, water supplied through the first two-position three-way valve is provided through the water tank of the water pump station. The balance weight water tank supplies water to the water tank of the water pump station through the second two-position three-way valve. According to the hydraulic balancer of the beam-pumping unit, automatic balance of the pumping unit can be achieved, the balance effect of the pumping unit is improved, energy consumption of the pumping unit is reduced, the service life of the pumping unit is prolonged, and therefore oil extraction cost is reduced.