The invention provides an automatic power flow adjustment method and system. The method comprises the following steps of S1, acquiring basic operation mode data when a power grid fluctuates; S2, calculating an adjustment step length based on the basic operation mode data and preset adjustment information; S3, adjusting the generator power and the load power through the adjustment step length; S4,calculating the power flow according to the adjusted generator power and the adjusted load power, determining whether the power grid is stable based on a power flow calculation result, and ending thepower flow calculation when the power grid is stable, otherwise resetting the adjustment step length and executing the step S3. The automatic power flow adjustment method provided by the invention realizes the iterative power flow mode adjustment, realizes an automatic mode, replaces the manual power flow adjustment to a certain extent, shortens the power flow adjustment work time, and improves the work efficiency.