The invention discloses a hydraulic spring balance automatic spray nozzle comprising a spray nozzle support, a spray nozzle head, a hydraulic adjustment block, an ejection block, a spring, a spray needle and a spray bowl. The spray nozzle support is provided with a through hole in the axis direction. The spray nozzle head is installed at the front end of the spray nozzle support. The spray bowl is installed at the front end of the spray nozzle head. The hydraulic adjustment block is installed at the tail end of the spray nozzle support. A hydraulic connector is arranged at the rear end of the hydraulic adjustment block. The spray needle is arranged in an inner hole of the spray nozzle head. The ejection block is arranged in an inner hole of the spray nozzle support. The rear end of the spray needle makes contact with the front end of the ejection block. The rear end of the ejection block is connected with the front end of the hydraulic adjustment block through a spring. The hydraulic adjustment block is provided with a hydraulic hole communicating with the cavity gap among the hydraulic connector, the ejection block and the hydraulic adjustment block. A feed hole is formed in the spray nozzle head. The hydraulic spring balance automatic spray nozzle can be automatically closed or opened so that raw material switching can be achieved, changes of the flow proportion can also be achieved, and the relative stability of the raw material pressure is kept in the flow proportion change process.