Superconducting Y-Ba-Cu-O thin films were prepared on MgO(100) substrate by aerosol-assisted chemical vapor deposition (AACVD). The process used a single solution sourer of Y, Ba and Cu beta-diketonates dissolved in tetrahydrofuran (THF). This liquid precursor was passed through an ultrasonic aerosol generator and transported into a CVD reactor where solvent and precursor evaporation and deposition occurred on heated substrate. Experimental details of this process were described and the effects of preheating temperature were studied in order to improve the quality of the deposited films. When the preheating temperature was 380 degrees C, films deposited at 815 degrees C had sharp transitions to the superconducting state about 88 K. The best superconducting films deposited by AACVD were prepared in oxygen partial pressure of 3.2 Torr at a deposition temperature of 815 degrees C.