Abstract: The sources and ways of the carryover in biochemical detection system and self-built detection system were analyzed by consulting literature. Reagents, reaction products, reaction conditions and components of the analytical system are the sources and ways of contamination. The supporting system is designed and controlled from the source of contamination of reagent formulation and improves the cleaning ability of the instrument. After the full traversal evaluation and the cross-contamination avoidance Settings, the contamination can be effectively cut off. By learning from the methods to solve the carryover of biochemical detection system, this paper provides strategies for solving the carryover of biochemical self-built detection system, and makes a specific analysis based on the case of UA detection of carryover in laboratory. There are many sources and complex ways of cross contamination in the biochemical analysis system, so maintaining the integrity of the detection system is an effective means to avoid cross contamination and a basic guarantee for the effectiveness of the detection system.