Spartina anglica, a plant that controls coastal erosion, is widely distributed throughout the world and is rich in cellulose, hemicellulose, and lignin. The hemicellulose from Spartina anglica can be extracted and hydrolyzed into monosaccharides and xylooligosaccharides under acid or enzymatic digestion conditions. In this study, an effective PMP(1-phenyl-3-methyl-5-pyrazolone)-derivatized HPLC (High performance liquid chromatography) method was developed for monitoring monosaccharides and xylooligosaccharides of Spartina anglica. With phosphate buffer (0.04 M, pH 8.06) as mobile phase A, and acetonitrile as mobile phase B, in which the elution gradient was set as A:B/79:21, the monosaccharides (glucose, xylose and arabinose) and xylooligosaccharides (xylobiose, xylotriose, xylotetraose, xylopentaose, xylohexaose) could be separated completely using the C18 column. This provides an economical, rapid, and efficient method for process monitoring in the bioconversion of Spartina anglica.