The invention provides a high-power function generator and a generation method. The high-power function generator includes: a function signal receiving module for receiving a required function signal; a direct current signal receiving module for receiving a direct current required by a direct current offset; and a direct coupled amplifier, a positive electrode of the input terminal of which is coupled to the output terminal of the function signal receiving module and an output terminal of the direct current signal receiving module, respectively. The function signal and the direct current signal are overlapped and amplified to output a high-power function signal. The high-power function generator is simple in structure and low in cost. Response of power and frequency of a generated signal is only limited to the performance of the direct coupled amplifier; the distortion factor of an output signal only depends on two factors of the distortion factor of a signal source and the distortion factor of the direct coupled amplifier; and the output frequency is only limited to the performance of the direct coupled amplifier, so that the high-power function generator and the generation method are widely applied to production and testing of a product.