In　order　to　solve　the　capacity　shortage　problem　in　power　system　frequency　regulation　caused　by　large-scale　integration　of　renewable　energy,　the　battery　energy　storage-assisted　frequency　regulation　is　introduced.　In　this　paper,　an　adaptive　control　strategy　for　primary　frequency　regulation　of　the　energy　storage　system　(ESS)　was　proposed.　The　control　strategy　combined　virtual　droop　control,　virtual　inertial　control,　and　virtual　negative　inertial　control.　The　virtual　inertial　control　was　used　to　reduce　the　frequency　change　rate,　and　the　virtual　droop　control　was　used　to　reduce　the　steady-state　frequency　deviation.　The　virtual　droop　control　and　the　virtual　inertia　control　were　adopted　in　the　frequency　deterioration　stage　to　slow　down　the　frequency　drop.　While　in　the　frequency　recovery　stage,　the　virtual　negative　inertia　control　worked　together　with　the　virtual　droop　control　to　accelerate　the　frequency　recovery.　Besides,　the　coefficients　of　the　control　methods　were　related　to　the　state　of　charge　(SOC)　of　ESS　to　avoid　over-charging　and　over-discharging　of　the　battery.　Finally,　a　simulation　model　was　built　in　MATLAB/SIMULINK,　and　case　studies　were　conducted　to　verify　the　proposed　control　strategy.　Results　showed　that　the　proposed　method　could　meet　the　demand　for　frequency　regulation　and　was　beneficial　to　the　cycle　life　of　ESS.