Abstract: Carp edema virus (CEV) causes significant economic losses in China's carp aquaculture industry and the ornamental fish import-export trade. Known for its high pathogenicity and mortality rates, CEV poses a serious threat to carp health. To achieve rapid on-site detection of CEV, we develops a diagnostic technique that combines recombinase polymerase amplification (RPA) with the CRISPR/Cas13a system. This technology enables isothermal amplification without the need for specialized equipment and operates at 37 °C. It provides specific nucleic acid detection at the single-molecule level for the virus and completes testing within 30 to 60 min. The detection limit is up to 1.256 copies·μL⁻¹, indicating high sensitivity and specificity. Results are interpretable through lateral flow test strips. This method is suitable for port quarantine, farm monitoring, and field surveys, enabling fast, accurate, and portable on-site testing. It significantly enhances detection efficiency while reducing turnaround times, providing a reliable technical solution for the prevention and control of CEV.