"粒度组成" can be translated into English as "particle size distribution" or "grain size composition", depending on the specific context.
"Particle size distribution" is a more commonly used and technical term, especially in fields like materials science, geology, and engineering, referring to the proportion of particles of different sizes in a sample.
"Grain size composition" is also acceptable, especially when referring to the composition of grains in a sedimentary rock or soil, but it is slightly less common in general technical usage.
In most cases, "particle size distribution" would be the preferred choice.