Abstract: Significant differences of physical and control structures between virtual synchronous generator (VSG) and synchronous generator (SG) lead to the poor transient power sharing in the isolated power system with SGs and VSGs. VSG will take the majority of the load and even short-time overload in the transient process due to faster regulation, which causes the insufficient utilization of inverter capacity and poor economy. To solve this problem, firstly, the reasons of poor transient power sharing are analyzed from the differences of frequency regulation, voltage regulation and output impedance between VSG and SG. Secondly, virtual speed regulation, virtual excitation and dynamic virtual impedance are added to traditional VSG control, so that the VSG can simulate the speed regulation characteristics, electromagnetic transient characteristics and output impedance of SG, and the transient power sharing between SG and VSG can be realized. Then, to ensure the fast transient response, traditional VSG control algorithm is remained in an independent operation mode. And the two modes can be switched smoothly by designing state tracking loop. Finally, simulations in PSCAD/EMTDC and Hardware-in-the-loop experiments based on RT-LAB verify that the proposed control strategy can effectively improve the transient power sharing in parallel with SG and maintain fast dynamic characteristics in an independent operation mode, the modes can be switched smoothly, and the method can be used in engineering.