Objective To analyze the reasons of invalid detections occurred in using three kinds of nucleic acid detection systems in our laboratory since 2016.Methods Analyze the numbers and types of invalid detections,for Roche Cobas S201 system from January to December 2016,Procleix Tigris system from January to September 2016,and Procleix Panther system from September 2016 to March 2017,respectively.Results The invalidation rates of Cobas s201,Tigris,and Panther systems were 0.90％ (402/44 838),4.01％ (2 960/73 835),and 1.34％ (1 093/81 741),respectively,and there were statistically significant differences between the three detection systems (P＜0.05).Except for the differences between Roche Cobas s201 and Panther 1404,there were statistically significant differences between instruments (P＜0.05).Failure of instruments,invalid detection of reagent calibrators,fault operation and sample quality are the causes of invalid detection.Conelusion The main reason of invalidation is instrument failure and reagent calibrator failmre.Invalid detections of nucleic acid screening is related on different detection systems.