Valve back compensation pump control hydraulic system with variable pressure difference and engineering machinery

The invention discloses a variable-pressure-difference downstream compensation pump control hydraulic system and engineering machinery. The system comprises an electric control pump, a variable-pressure-difference valve, a proportional control valve and a downstream compensator. An outlet of the electric pump is respectively connected with inlets of the variable differential pressure valve I and the variable differential pressure valve II; an outlet of the variable differential pressure valve I is connected with an inlet of the proportional control valve I; an outlet of the first proportional control valve is connected with an inlet of a first downstream compensator, and an outlet of the first downstream compensator is connected with a first executing mechanism. An outlet of the variable differential pressure valve II is connected with an inlet of the proportional control valve II; an outlet of the second proportional control valve is connected with an inlet of the second downstream compensator, and an outlet