In　order　to　protect　Chinese　ancient　buildings,　the　Shen-Wu　Gate　in　the　Forbidden　City　was　taken　as　an　example　to　study　its　stochastic　seismic　response　characters　by　absolute　displacement　solution　based　on　pseudo　excitation　method　and　harmonic　response　analysis　of　ANSYS　program.　Finite　element　model　of　Shen-Wu　Gate　was　built.　Then　by　modal　analysis　basic　frequency　of　the　structure　was　obtained;　By　harmonic　response　analysis　displacement　and　acceleration　response　power　spectral　density　of　typical　nodes　under　even　ground　stationary　random　excitation　were　obtained.　Constitution　parameters　were　also　discussed.　Results　show　that　basic　frequency　of　Shen-Wu　Gate　is　1.07　Hz,　under　even　ground　stationary　random　excitation　peak　values　of　response　power　spectral　density　of　the　structure　occur　at　its　basic　frequency　value,　constitutions　such　as　tenon-mortise　joints,　tou-kung,　cejiao,　floating　column　base　and　so　on　are　all　practical　for　earthquake　resistance.