Copper is a necessary trace element in the human body, with adults requiring about 2 mg per day. Functional materials containing Cu2? bring great convenience to life, but their released Cu2? from these materials are harmful to human health and the environment. Regulators have proposed allowable emission standards for copper (Ⅱ), among which “Drinking Water Sanitation Standard” (GB5749-2022) specifies 1.0 mg/L, with stricter standards in industrial emissions and sewage treatment plant pollutant discharge standards. The “Iron and Steel Industry Water Pollutant Discharge Standard” (GB13456-2012) sets 0.5 mg/L, while fishery requirements are the strictest under “Fishery Water Quality Standard of the People's Republic of China” (GB11607-89) limiting 0.01 mg/L. These regulations underscore the need for sensitive and selective detection of low concentrations of Cu2? for environmental, industrial, and human health applications.In this study, a tapered optical fiber sensor coated with CS-PVA composite coating is designed. The micro/nanostructure consists of a single-mode tapered optical fiber sensor whose tapered region generates evanescent waves. High-sensitivity detection of Cu2? in aqueous solution was achieved through coating a CS-PVA polymer composite film on the surface of the fiber's waist-cone region. Ion imprinting technology was applied to enhance the sensor, using glutaraldehyde as a crosslinker to strengthen the polymer network through the crosslinking agent, thereby enhancing metal ion adsorption. Regeneration using hydrochloric acid induces protonation of amine groups, creating repulsion between NH?? and adsorbed Cu2? for release.The ion-imprinted sensor demonstrated specificity when exposed to Cu2?, Cd2?, Fe3?, Co2?, and Pb2? confirming selective Cu2? detection. While the sensor primarily detects Cu2?, it could be adapted for other heavy metal ions through polymer template modification, showing great potential in heavy metal detection across environmental monitoring, industrial effluent testing and remote monitoring.Within 0~100 μmol/L Cu2?, the sensor reached 85.131 6 pm·μmol?1·L sensitivity with a limit of detection (LOD) of 0.388 μmol/L and linear response (R2=0.980 76). The improved ion-imprinted sensor exhibited specificity toward Cu2??. This easily fabricated sensor combines operational simplicity with high Cu2?? sensitivity while maintaining adaptability for other heavy metal ions through template ion substitution.The growing industrial demand underscores the importance of reliable Cu2?? detection for environmental and human health. We developed a simple, yet sensitive fiber-optic sensor for Cu2??. Three sensor configurations were fabricated via dip-coating: uncoated, CS-PVA-coated, and CS-PVA ion-imprinted variants. Experimental results demonstrate that, within 0~100 μmol/L Cu2?? concentrations, the CS-PVA-coated sensor achieved 85.131 6 pm·μmol?1·L sensitivity, an LOD of 0.388 μmol/L, and linear response (R2=0.980 76). The improved ion-imprinted sensor showed specificity toward Cu2?. Combining ease of fabrication with operational simplicity, this platform enables specific Cu2? detection while remaining adaptable for other heavy metal ions through imprinting modifications.