MicroRNA (miRNA) is closely related to the occurrence and development of certain diseases and can be used as a diagnostic marker. Conventional methods for the detection of miRNA are time-consuming and complex. Herein, a portable rapid miRNA detection system was designed. This system records the fluorescence intensity of the marker that is amplified via rolling circle amplification using a photoelectric detection technique, and analyzes the fluorescence data to obtain the changes in miRNA. Through our experiments, we observed that for reagent concentrations in the range 0.1-1 μmol, the linearity of the fluorescence intensity detected by the miRNA fluorescence detection equipment was less than ±5%, and the repeatability was ≥95%. Our roll amplification experiment involving the coronary heart disease diagnostic marker, miR-499, confirmed that the portable rapid miRNA detection system can detect miRNA quickly and effectively.