Rapid and simple analysis for the multiple target pathogens is critical for patient management. CE‐SSCP analysis on a microchip provides high speed, high sensitivity, and a portable genetic analysis platform in molecular diagnostic fields. The capability of separating ssDNA molecules in a capillary electrophoretic microchannel with high resolution is a critical issue to perform the precise interpretation in the electropherogram. In this study, we explored the potential of poly(ethyleneoxide)‐poly(propyleneoxide)‐poly(ethyleneoxide) (PEO‐PPO‐PEO) triblock copolymer as a sieving matrix for CE‐SSCP analysis on a microdevice. To demonstrate the superior resolving power of PEO‐PPO‐PEO copolymers, 255‐bp PCR amplicons obtained from 16S ribosomal RNA genes of four bacterial species, namely Proteus mirabilis, Haemophilus ducreyi, Pseudomonas aeruginosa, and Neisseria meningitidis, were analyzed in the PEO‐PPO‐PEO matrix in comparison with 5% linear polyacrylamide and commercial GeneScan™ gel. Due to enhanced dynamic coating and sieving ability, PEO‐PPO‐PEO copolymer displayed fourfold enhancement of resolving power in the CE‐SSCP to separate same‐sized DNA molecules. Fivefold input of genomic DNA of P. aeruginosa and/or N. meningitidis produced proportionally increased corresponding amplicon peaks, enabling correct quantitative analysis in the pathogen detection. Besides the high‐resolution sieving capability, a facile loading and replenishment of gel in the microchannel due to thermally reversible gelation property makes PEO‐PPO‐PEO triblock copolymer an excellent matrix in the CE‐SSCP analysis on the microdevice.