The present invention relates to a sample plate for matrix-assisted laser desorption ionization (MALDI) mass spectrometry having a stable glyco-affinity layer of a carboxyalkyl boronic acid or carboxyaryl boronic acid and a preparation method of the sample plate. The sample plate shows excellent selectivity for glycoprotein, and can be easily and cost effectively prepared. The sample plate is useful for glycoprotein analysis by MALDI mass spectrometry.