A fluorescent sensor array has been developed based on conjugated polymers (CPs) having six different skeletons for the detection of tetracyclines (TCs), which are known as environmental pollutants. CPs were synthesized from confined nanoreactors in a controlled manner. The fluorescent response occurs through the fluorescence resonance energy transfer (FRET) effect. By utilizing linear discriminant analysis (LDA), effective differentiation of TCs was accomplished with a very low detection concentration (66 nM). Moreover, the sensor array exhibited a highly sensitive ability to quantitatively distinguish different concentrations of TCs. Finally, the sensor array's potential for detecting TCs in aqueous solutions has been successfully demonstrated, widening its applications in practical environments. With simple preparation process, a low cost of detection and high sensitivity, the experimental results indicate that the CP-based sensor array is a promising platform for the sensitive and quantitative detection of TCs, and provides a good reference for future scientific research.