This paper deals with some important problems on the process of preparing proton sensitive nuclear emulsion.By controlling the concentration of bromide ions during emulsification, the size of the silver halide grains is made quite uniform. In order to raise the sensitivity of emulsion, we select the optimum condition at the ripening stage and add the sensitizer "triethanolamine" before coating. Latent image fading is restricted by adding gold salts into the finished emulsion and the fog is minimized by purifying the photographic gelatin.After systematical investigation on the process of preparation, it is now possible to "produce proton sensitive nuclear emulsions with the same characteristics. They are about the same as those of "Ilford C2" emulsion for nuclear research.