Since　the　attribute　aggregation　of　the　evidential　reasoning　approach　with　multiple-level　hierarchical　structures　is　implemented　in　a　recursive　way,　the　aggregation　times　are　the　number　of　the　branch　nodes　of　attribute　tree,　which　results　in　a　large　amount　of　calculation.　To　reduce　the　amount　of　calculation,　a　non-recursive　aggregation　approach　is　proposed　and　its　time　complexity　is　compared　with　that　of　the　recursive　approach.　To　explore　the　accuracy　and　the　nonlinear　characteristics　of　the　non-recursive　approach　to　dealing　with　different　belief　distributions,　the　belief　degrees　and　the　utilities　of　the　aggregated　attribute　are　calculated　in　terms　of　the　belief　structures　of　harmony,　quasi-harmony　and　conflict,　respectively.　The　nonlinear　characteristics　of　the　two　aggregation　approaches　are　analyzed　based　on　the　comparison　of　formula　derivation　and　experimental　results,　and　the　accuracy　of　the　non-recursive　approach　is　examined　from　the　angle　of　relative　errors.　The　experimental　results　and　the　numeric　example　show　the　effectiveness　of　the　proposed　approach.