The invention provides a power grid dispatching operating risk early warning method based on a risk source. The method comprises the first step of acquiring weather state information at the positions of power grid dispatching operating devices and acquiring the fault rate and the obsolescence degree of each operating device, wherein the weather state information includes a plurality of pieces of meteorological index data, the second step of subtracting each piece of meteorological index data from a corresponding preset threshold value, comparing each difference value with the corresponding preset threshold value and obtaining a meteorological index value corresponding to the piece of meteorological index data, the third step of determining meteorological awful factors according to all the meteorological index values, and determining the fault rate correction value of each operating device according to the corresponding meteorological awful factor, the fourth step of calculating the reliability degree of each operating device according to the obsolescence degree, the fault rate and the fault rate correction value of the operating device, and the fifth step of conducting early warning on power grid dispatching operation according to the reliability degrees of all the operating devices. By means of the power grid dispatching operating risk early warning method, the accuracy of estimation of the reliability degrees of the power grid operating devices is improved, and misinformation during power grid operating risk early warning is avoided.