An automatic waste water treatment control mechanism comprises an on-site controller. The on-site controller is connected to a water pump control box, an electric valve control box, a flowmeter, a liquidometer, an on-line turbidity meter, a pressure transmitter, a sludge amount sensor and a dose detection instrument of an input device, and is connected to a water pump control box, an electric valve control box and an electric actuating mechanism of an output device. A remote monitoring computer is connected to the on-site controller via a wired network or serial ports, and is connected to cellphone terminals via a wireless network. The mechanism fully utilizes collected information for comprehensive comparison and determination, performs highly efficient and scientific processing operations, and controls dosage reasonably while ensuring the water treatment quality, so that secondary pollution is avoided. The mechanism combines fixed and mobile modes to ensure comprehensive and convenient monitoring. And a function that displays preliminary causes of a fault provides great convenience for maintainers.