The ever-increasing large-scale infeed of renewable generation in power systems, has resulted in the low inertia and deteriorated frequency issues. To enhance the system frequency stability, this paper proposes a reserve and inertia multi-objective optimization model, which explicitly taking into account the frequency regulation capability of the virtual synchronous generators(VSGs). The virtual inertia, virtual damping coefficients, and frequency droop coefficients of the VSGs are simultaneously optimized to ensure that the rate-of-change-of-frequency, frequency nadir, and quasi-steady frequency following a credible contingency will not beyond the pre-described limits. NSGA-II is used to obtain the pareto front and the PC-TOPSIS technique is utilized to select the preferred solution. Simulation results on the modified IEEE 39-bus system verify the effectiveness of the proposed model.