The invention provides a preparation method of a
photocathode. The preparation method comprises the following steps: providing a substrate, an
alkali metal evaporation source and a non-
metal evaporation source; and realizing non-
metal intermittent deposition and
alkali metal continuous deposition on the surface of the substrate by adopting an
alkali metal evaporation source and a non-
metal evaporation source in a high-vacuum environment so as to prepare the corresponding
photocathode. According to the method, non-metal intermittent deposition and alkali metal continuous deposition are adopted, it is ensured that in the
photocathode preparation process of different devices, different batches of photocathodes prepared by different persons keep almost consistent high
quantum efficiency, and the
quantum efficiency of 100% of the photocathodes is maximized; the non-
substrate surface can be inhibited from generating a photocathode with high
quantum efficiency by non-metal intermittent and alkali metal continuous deposition, and the interference of
dark current in the preparation process is remarkably reduced; and compared with
sequential deposition and co-evaporation, the preparation difficulty is greatly reduced, the consumption of an evaporation source is greatly reduced, the preparation time is shortened, the service life of the photocathode is prolonged, and a foundation is laid for realizing industrial full-automatic production of the photocathode.