The effects of the H+. C+. N+, F+, and Ne+ (25–200 keV)ion irradiations have been investigated by means of SEM, room temperature resistance measurement and aqueous degradation test. The room temperature resistance increases exponentially with irradiation doses. At lower dose, the annealing process is dominent, while at higher dose, the resistance increasing process is dominent. A reduction in the thickness induced by ion irradiation has been observed. The aqueous experiment shows that passing current will speed up the degredation and N+ implantations can increase the resistance of the YBCO thin film against attack by water.