The　secure　consensus　problem　of　multiagent　systems　with　fixed　topology　and　external　disturbances　is　investigated　in　this　paper.　Along　with　external　disturbances,　the　studied　multiagent　system　is　also　subjected　to　denial-of-service　(DoS)　attacks.　First,　some　graph-based　Lyapunov　functions　are　presented　for　the　robust　consensus　analysis.　Second,　the　duration　and　attack　frequency　are　introduced　to　quantitatively　analyze　the　DoS　attacks＇　effects　on　the　consensus.　Third,　the　gain　of　the　controller　is　acquired　by　solving　an　algebraic　Riccati　equation　(ARE),　which　can　always　be　guaranteed　compared　with　solving　linear　matrix　inequalities　(LMIs).　Finally,　a　numerical　simulation　of　a　microgrid　test　system　is　provided　to　demonstrate　the　effectiveness　of　the　proposed　strategy.