Abstract: Nine reactive aldehyde dyes were synthesized by “grafting” colorant groups to the α-C of several aldehyde compounds. The structures of the target products were characterized by means of FTIR, UV-vis, and ESI-MS. Aluminum-pretanned wet-white sheep leather was chosen as a substrate for the application experiments, and four dyeing property indexes, i.e., substantivity (S), exhaustion (E), fixation (F) and reactivity (R) were measured. The results indicated that, without the addition of neutral salts and under mild conditions (T = 35-45 °C，pH = 4.0-6.5), all the dyes could dye wet-white leather within 1.5 h, and the dyed leather possessed a satisfactory washing-fastness. Key words: aldehyde; reactive dyes; identification; application