Abstract: In order to solve the concealment carryover contamination in clinical chemistry assay, a versatile judgment standard and a solution for reagent carryover contamination were designed. The reagent carryover contamination of 930 combinations between 31 types in-vitro diagnostic kits of BioSino were evaluated by using automatic biochemical analyzer (Abbott c16000), and a new judgment standard was put forward which is conducive to finding out those concealed carryover contaminations. Then a special cleaning procedure was designed. Results showed that 10 combinations with carryover contamination were identified by using traditional standard, and 5 more combinations with carryover contamination were picked out by using the new standard. The special cleaning procedure was used to the 15 combinations, in which the contamination rates of the 15 combinations were all significantly reduced and carryover contaminations of them were all eliminated.