In analysing the Image quality, one of the most important things to be considered is the granularity at a given emulsion speed. To enhance the image quality, the granularity should be lowered by the suitable methods, such as controlling the design of emulsion, grain size and structure, the distribution state of grains in the emulsion, etc. In this paper, the relations between the AgX grain structure and granularity are studied as a way of lowering granularity. According to the results, it is found that the grain structure is a very important factor for determining the granularity characteristics.istics.