To seek a photocathode with good stability and repeatability in an ultrahigh vacuum system, activation and recesiation experiments are carried out on reflection-mode GaAlAs and GaAs photocathodes grown by metalorganic chemical vapor deposition, and the spectral response curves and photocurrent decay curves are measured after Cs/O activation and recesiation. Experimental results show that the photocurrent decay lifetime for GaAlAs photocathode illuminated by white light with an intensity of 100 lx is longer than that for GaAs photocathode after Cs/O activation and recesiation under ultrahigh vacuum condition. Moreover, GaAlAs photocathode exhibits a coincident blue-green response capability and a photocurrent decay lifetime after multiple recesiations, reflecting the superiority in stability and repeatability for GaAlAs photocathode operating in the vacuum system, and may provide an experimental guidance for exploring marine vacuum detectors and vacuum electron sources.