In this work, micro-scale porous carboxyl polystyrene microspheres (PS) were prepared using seed polymerization. Quantum dots (QDs) were used as fluorescent molecules to synthesize QDs with different emission wavelengths and successfully loaded into porous microspheres to form fluorescent coding microspheres (QDs@PS). Subsequently, serum samples of patients with acute leukemia (AL) were detected, and the antigen in the serum was quantitatively analyzed using flow cytometry. Scanning electron microscope (SEM) and flow cytometry images showed that the microspheres were regular and uniform in size. Fluorescence microscopy showed that the QDs permeated uniformly into the whole microsphere. In addition, QDs@PS showed good fluorescence stability, no QD leakage was observed, and the QDs@PS maintained its fluorescence for a period of at least two weeks. The use of fluorescence spectroscopic analysis for the detection of human immunoglobulin G (IgG) showed that the carboxyl groups on the surface of fluorescent microspheres are beneficial for the efficient covalent binding of biological macromolecules, which can be used for sandwich immunosandwich reaction coupling with leukemic high expression antigen interleukin 6 (IL-6). Combined with serum samples from leukemia patients, the fluorescence of QDs was detected by flow cytometry, and the mean fluorescence intensity (MFI) was calculated to determine the content of IL-6 in the serum. These results indicate that the designed optically-encoded microcarrier can be successfully applied to high-throughput and multichannel biomolecular analysis and has great potential in blood disease detection and diagnosis.