How　to　solve　disease-diagnosing　problem　effectively　by　the　aid　of　Artificial　Intelligence　Computer　has　been　being　a　mainstream　of　Intelligent　System　researching　and　development.　Heretofore,　performance　of　the　well-known　native　Uncertainty　Reason　Resolution　method　still　is　unsatisfactory　to　professionals.　This　paper　pioneers　the　concept　of　Associative-Pivot　Factor　and　its　Certainty　Index　Speculation　algorithm,　and　on　this　base　designs　A　novelty　Machine　Diagnosing　Algorithm　based　on　the　Certainty　Reason　of　Associative-Pivot　Factor.　Results　and　analysis　demonstrate　that　the　method　exhibit　a　better　efficiency　than　man-expert　individual　and　the　native　CF　Method.　Generally　speaking,　it　manifests　an　accurate　rate　of　diagnosis　over　82%　and　possesses　the　capacity　to　expand　diagnosing　capability　of　man-expert.　©　(2014)　Trans　Tech　Publications,　Switzerland.