With the continuous access of distributed generation units, the DC microgrid gradually presents the characteristics of low inertia and weak damping, and the DC bus voltage will change or lose stability due to power disturbance. To regulate DC bus voltage, a control strategy based on virtual inertia is proposed in this paper. To improve the virtual inertia value, the first-order filtered link time constant is introduced as the new degrees of freedom to obtain greater virtual inertia while keeping the circuit stable. In addition, the adaptive virtual inertia control strategy mitigates the problem of large virtual inertia inhibiting quick grid voltage recovery, so that the virtual inertia control has the dual effect of suppressing voltage fluctuations when deviating from the reference voltage and reducing voltage adjustment time when approaching the reference voltage. Finally, the proposed control strategy is validated by simulation while considering the load variation.