Alcohol-water complex clusters were studied by using multiphoton ionization technique and time-of-flight mass spectrometer. Laser with 355 nm wavelength was used as ionized source, protonated cluster ions (ROH)n (H2 O)H + and (ROH)n H + were observed where R=CH3 or C2 H5 . The formation of (ROH)n (H2 O)H + is mainly through proton transfer reaction intra alcohol-water clusters ions after laser multiphoton ionization. Some possible geometric structures of (CH3 OH)n (H2 O)H + with relatively small sizes were guessed using ab initio calculation method. The structures show that (CH3 OH)H + trends as the ion’s center, and then it combines with other methanol or ethanol molecule to form the final stable complex cluster ions.