This papre proposes a new second order active disturbance rejection (ADRC) frequency regulation method to solve the frequency regulation problem of virtual synchronous generator (VSG) system caused by load cutting/cutting in isolated island state. Firstly, a new nonlinear function with better smoothness and continuity around the origin is designed, and based on this new function, a new second-order ADRC method is designed.Then, the ADRC method is combined with VSG system. When the frequency deviation exceeds the set range, the secondary frequency regulation is started to make the frequency quickly recover to a small range. Finally, the proposed method is compared with the traditional VSG control strategy and the traditional ADRC secondary frequency regulation algorithm, and the superiority of the proposed secondary frequency regulation algorithm is verified.