Nucleic acid testing is increasingly being utilized in the detection of foodborne pathogens. The implementation of fully automated and enclosed nucleic acid testing systems has the potential to significantly reduce manual labor and testing time for operators. Therefore, the development of such systems has become a focal point in current research. In this study, the focus is on addressing how to achieve fully automated detection at low cost. The research is primarily centered on the design of key functional modules required for the detection process including nucleic acid extraction, heating, and optical detection. The detection process does not require manual supervision or participation and does not require professional technical personnel, thereby reducing the usage cost. By simply adding a sample, it can simultaneously screen and analyze different types of foodborne pathogens, making it advantageous for the analysis and detection of complex samples. The design and manufacturing of the device are cost-effective and highly applicable. By adjusting the reaction program, the fully automated nucleic acid detection device can achieve compatibility with various amplification reactions, demonstrating its broad application prospects in the field of Cronobacter sakazakii analysis.