Purpose　This　paper　aims　to　provide　a　symplectic　conservation　numerical　analysis　method　for　the　study　of　nonlinear　LC　circuit.　Design/methodology/approach　The　flux　linkage　control　type　nonlinear　inductance　model　is　adopted,　and　the　LC　circuit　can　be　converted　into　the　Hamiltonian　system　by　introducing　the　electric　charge　as　the　state　variable　of　the　flux　linkage.　The　nonlinear　Hamiltonian　matrix　equation　can　be　solved　by　perturbation　method,　which　can　be　written　as　the　sum　of　linear　and　nonlinear　terms.　Firstly,　the　linear　part　can　be　solved　exactly.　On　this　basis,　the　nonlinear　part　is　analyzed　by　the　canonical　transformation.　Then,　the　coefficient　matrix　of　the　obtained　equation　is　still　a　Hamiltonian　matrix,　so　symplectic　conservation　is　achieved.　Findings　Numerical　results　reveal　that　the　method　proposed　has　strong　stability,　high　precision　and　efficiency,　and　it　has　great　advantages　in　long-term　simulations.　Originality/value　This　method　provides　a　novel　and　effective　way　in　studying　the　nonlinear　LC　circuit.