An online detection system based on single-chip microcomputers comprises multiple sensors arranged as required, and also comprises a host computer. Each sensor is connected to one single-chip microcomputer. The single-chip microcomputers are in communication connection with the host computer respectively. Also disclosed is a control method for the online detection system based on single-chip microcomputers. The method comprises: first, performing first analysis processing on results by means of single-chip microcomputers, then performing classification-based processing by using a host computer, and performing intelligent analysis on the detection results, and finally displaying specific detection results. A person does not need to again perform analysis and can directly take a measure according to the analysis results, thereby improving the detection efficiency.