The power grid has the characteristics of non-linear load and intermittent energy supply. The accuracy of dynamic frequency measurement is susceptible to unsteady classification and noise. To solve this problem, this paper studies dynamic frequency measurement technology from both aspects of algorithm and hardware. The dynamic frequency measurement method of fundamental and harmonic method based on complex Simpson is proposed. The frequency variance expression of the proposed method under noisy condition is deduced theoretically. And the power signal conditioning and sampling circuit with strong anti-interference ability is designed in detail. The proposed method can effectively eliminate the influence of unsteady components in the power grid signal by using the principle of complex Simpson integral. The designed circuit and anti-interference method can reduce external interference to dynamic frequency measurement. The experimental results show that the proposed method can achieve dynamic frequency measurement of fundamental and harmonic with high-precision.