Spectroscopic observations were made for a sample of 263 stars from three young open clusters IC 1805, NGC 654 and NGC 6823 with CCD detectors in the blue and yellow-red spectral regions. MKK types were properly determined for these stars by carefully comparing spectra of program stars with those of a complete grid of MKK standards, which were observed with the same instruments as the program stars. For most of the observed stars precise MKK types were assigned for the first time. A few of early-type emission-line stars were discovered or confirmed. The presence of Be stars in the studied clusters is discussed. Spectra of the observed MKK standards also reveal lots of features showing temperature or luminosity effect in the yellow-red region, which helped in our stellar spectral classification.