The effect of hot cleaning and ion cleaning for photocathode glass substrate on imp roving the photocathode sensitivity is researched. It is shown from the analysis of glass ingredients of different glass substrates that the alkali metal content in glassmay affect the photocathode sensitivity. It is shown from the analysis of surface tension that the hot and ion cleaning of photocathode glass substrate can increase the certain degree. It is also shown from XPS analysis that the ion cleaning can be used to imp rove the sensitivity of photocathode, however, an excess ion cleaningmaycause C contamination to decrease the stability of photocathode sensitivity.