Because　of　the　randomness　and　uncertainties　of　earthquake　and　its　structures,　it　is　a　natural　choice　to　analyze　and　evaluate　the　risk　of　earthquake　in　the　way　of　seismic　risk　analysis.　Effective　prediction　of　earthquakes　can　minimize　property　losses　and　protect　citizens＇　safety.　In　this　article,　Bayes　rule　was　used　to　make　a　simple　prediction　of　the　risk　of　a　strong　earthquake　in　a　certain　area.　Then　we　conducted　probabilistic　seismic　risk　analysis　(PSHA)　to　tackle　the　problem　of　a　specific　earthquake　about　where　the　earthquake　will　occur,　how　big　the　earthquake　will　be　and　when　will　the　earthquake　occur.　Furthermore,　we　dived　into　spatial　uncertainty,　temporal　uncertainty,　and　size　uncertainty,　respectively.　Since　earthquake　intensity　is　significant　for　seismic　vulnerability　analysis,　PGA　(peak　ground　acceleration)　was　used　as　the　index　of　earthquake　intensity　in　this　article.　To　be　more　specific,　Wenchuan　city　in　Sichuan　province　in　China　was　chosen　as　the　subject.　Finally,　seismic　risk　analysis　was　performed　and　the　failure　probability　of　the　system　was　gained.　©　Published　under　licence　by　IOP　Publishing　Ltd.