The invention provides an analytic solution method for aggregation of generators. According to the analytic solution method, voltage multi-transformation ratio influence generated when all the generators are transferred to an imaginary common bus in the aggregation process is accurately taken into consideration, and it is ensured that the power input into a power grid is not changed before and after equivalence. The current input into the power grid by the generators serves as a carrier representing the characteristics of the structure of a generator model, and therefore each generator is described as a time domain coefficient matrix form composed of structure parameters and the operation state of the generator. The conditions of the current input into the power grid before and after aggregation are inspected, the current phasors of the generators to be aggregated and the current phasor of an equivalent machine are transferred to a D-axis and a Q-axis of an entire power grid synchronization plane through a coordinate system transformation method, it is ensured that projections are the same, and therefore equivalent generator high-order (six-order) model parameters are directly obtained in a non-iterative mode in the time domain. The analytic solution method for aggregation of the generators is good in universality, and overcomes the defect that a frequency domain iteration solution method can not carry out solution accurately due to unreasonable arrangement of a working point or unreasonable selection of a searching direction, overcomes the dependence on a generator detailed model, and is small in calculation amount, high in efficiency and adaptive to the dynamic equivalence simplification application of a large-scale power grid.