The invention discloses an automatic optimization power generation control system based on a water level change rate. The system reads the real-time data from a monitoring system, carries out calculation and analysis, carries out the condition judgment at regular time, and transmits the control operations, such as starting, stopping, load adjustment, etc., to the monitoring system, and the monitoring system issues the control operations to an in-situ control unit LCU for unit power generation control. The load adjustment control is conducted according to a water balance principle that the difference of the reservoir-in water quantity and the reservoir-out water quantity is equal to change of the water storage quantity of a reservoir, if the water level rises, it shows that the reservoir-out water quantity is smaller than the reservoir-in water quantity, and under the condition that a water head is normal, load can be increased properly; if the water level drops, it shows that the output water volume is larger than the input water volume, and when the water level is smaller than a limit value, the load can be reduced according to the water level dropping rate, and according to the principle, the hour change rate of the water level is calculated under the current load condition. The automatic optimization power generation control system of the invention provides a powerful guarantee for realizing the unattended operation and few-person on-duty operation of a hydropower station.