A robust capillary electrophoretic method has been established to separate aminosaccharides including glucosamine, galactosamine, N-methyl-glucamine, N-acetyl-glucosamine and amino glucuronic acid. All the aminosaccharides were dansylated fast under microwave irradiation at 385 W for 6 min (about 50-fold faster than common methods) and detected via on-line UV adsorption at 214 nm. Baseline separation of the dansylatied products was achieved in 20 min using a running buffer of 320 mM borate at pH 9.50. Quantitation of glucosamine in osteoarthritis tablets was then conducted. A linear working range was found in between 2.00 μg/mL and 1.80 mg/mL with linear regression coefficient of 0.9964. The limit of detection reached 1.00 μg/mL glucosamine (signal-to-noise, S/N = 3). Recoveries were determined by spiking a known amount of glucosamine in tablet-extracted solutions, giving a range of 88.0–99.7%. The run-to-run relative standard deviation was 0.24% (n = 5) for migration time and 2.72% for peak area.